Making a Tower Defense Game Part 9


This is week 9 of my journey of making a Tower Defense game. To see previous parts, here is Part 8, Part 7Part 6Part 5Part 4, Part 3, Part 2 and Part 1

I thought that there was going to be nothing else to talk about after the previous post since a lot of content is done. But there is still stuff to talk about, and I will go through what I have done for the past week (aside from final phase testing and polishing – a little bit on that in awhile).

Drawing the last map for the game


The is the last map to be drawn for the game. This was a side-map that I had left as a last priority and I really love this map. Everything from the texture to the colours was fun to do. It was also my last time setting up the waypoints and writing the grid array. Farewell, maps.


I think I kind of like all of the maps I drew toward the end of development because I just get so much inspiration when there are long intervals between each map I draw. I went with a very ‘dusty’ old theme for this map, using desaturated colours, which is very different from the sunny maps. I really like how ‘old’ the Hut appears to be. I should have added a few cracks and holes now that I think about it.

I used a basic texture, but I really like how some textures emote and make this game more interesting to look at. Oh, the Hut spawns monsters. In case that wasn’t obvious from the way the map pathway was laid out.


The game I’m making has grown a lot since 2 months ago and although I started out with a sandbox-like tower defense, it now has a lot of features and content that sets it apart from most other tower defense games. I didn’t have that aim in mind when I first started though – I don’t try too hard to be different and as mentioned in one of my previous posts, making a super unique game with never-before-seen mechanics is not exactly my top priority.

I’m looking forward to letting people play this game, especially with some of the cooler stuff and animations I put in the past few weeks.

Introducing: Healing Runes

Oh, and just for this map, I also drew and coded the final rune to be in this game – the Healing Rune. The name probably already implies what the rune does, but here’s a breakdown of all the runes in my game:

Rune Descriptions


The runes are drawn to scale with one another. I didn’t actually mean to display the Runes and their information in such a presentable (and colorful) way. They look like the official tutorial or ‘help’ screens in the game but they aren’t.

Creep behaviour

I actually programmed a few unique ‘behaviours’.

Previously, my larva creeps (aka low HP + huge quantity creeps) move in single file. This usually isn’t a problem for normal creeps. But since larva spawn in bunches, it becomes harder to see individual larva when there’s so many of them because they overlap.


So I made them such that they actually zig zag around, with each individual larva having its own random zig zag. This is not only more realistic, but makes them more distinguishable and looks so much cooler.


The other behaviour I made work today was the Hadron Flyer, a special boss that IS ABLE TO TAKE OFF from the default pathway and FLY TOWARD THE END.


Basically, he converts from a ground-moving creep to a flyer, which can ignore the pathway and fly immediately to the exit. Of course, I had to bypass some limitations to make that happen. Now it’s not exactly overpowered because the player is still able to prevent this.


The movement looks simple but you got to be aware of a few things that need to happen when it takes off from the ground:

  • set its Flyer flag to true (to take into account modifiers like +100% damage to flying enemies)
  • change its ground waypoints to that of a Flyer
  • set its new end position
  • rotate the sprite toward its new end position based on its new calculated direction from current position
  • disable its acceleration (because it should not keep moving faster and faster now that it is already in the air)

This plane has a passive ability that increases its speed as it travels along a straight path. Take-off only occurs if the plane’s speed reaches 3. And this is preventable with Slow Turrets. I really like the idea of the plane taking off when its speed gets high. But this is the only boss with this ability and you only fight him on one of the optional side maps, so it’s a very rare behaviour and I doubt the player can actually experience it since all he needs is one slow turret to stop the plane from taking off. Still, it was fun to see this work.

Once he is mid-air, he is forever mid-air



I have also seem to finalized the upgrades in the game and their balancing/costs are about 80% settled. There are still two upgrades I have yet to balance.

I’m also converting some of the anti-alias-ed icons to pixel art so they look consistent in the overall skill icon design. And it was also the first time in a long time I went back to Paint, which was the software I originally used to create those skill icons years ago.


Yes, the pixel icons were made years ago with Paint (they were originally made for fun without the intention of actually using them as a game graphic). I merely made a few modifications to make them look up to par with my current graphics standard.

Loading Optimization

I haven’t yet found the best way to do loading, but because I use an atlas now, the game loads EVERY background map from the beginning. It no longer loads individually, which is what is done previously.

With 42 maps in one atlas, playing any map simply loads all 42 map graphics when I only need one. I don’t notice any delay on my computer, and my levels still insta-loads. But this can be a huge problem for players with slower computers. So what I do is to use static variables to store the Sprites.

SpriteManager singleton class

This way, they don’t get destroyed when the player quits the level. He can go roam around in the main menu, come back and play the level and the background will be already pre-loaded and waiting for him. He doesn’t have to wait for the backgrounds to reload if he has entered a level before.

Simply put it, this should cut level loading times after the the first play. The effect is probably minimal if you already have a fast computer though. I’m still trying to see if there’s a better solution so I can do this for all my sprites without needing to make 100 static variables for 100 graphics.

Level Select Polishing/Improvements

The Level Select now scrolls much faster. I think it is due to the recent optimizations I made. There used to be a split second freeze when changing pages. But now it so smooth that I coded ‘animated’ moving bars. Notice how the bars move up and down as I switch pages:


It makes the level select look so much better and I really love the effect that there are 3 coloured bars and they all animate smoothly when I scroll through the Level Select.

New Structure


The Unlimitor is a newly added structure in the game. When you build towers near it, they don’t count toward your total tower limit. (There is a maximum limit to how many towers you can have on the map at once).

This is a really cool concept I wish I explored more on. I don’t have space in the game to squeeze in more structures so I only added this to two of the final maps.

I made this structure for the final map because the final map is extremely large and the player would appreciate an increased limit.


I drew a ‘destroyed’ state so that player has to repair it before receiving the bonuses, but I removed it later on because I feel I have too many ‘broken and repair-able’ structures in the game that almost everything needs repairing, so this structure starts off REPAIRED. That’s like a free lunch in this world.

Oh, not sure if I mentioned this before but you not only repair stuff.

You also destroy stuff. How awesome is that?

Big Foot + Number Formatting

Big Foot mini-boss and his 3 children

Notice also that in the information panel on the right side of that screenshot, I’ve also changed the way number displays work.

HP: 8,080,000,000 –> 8.080B

I have added a new option that when enabled, numbers or values above 99,999 are optionally displayed as 105k, or 1.5M instead of 1,500,000.

This is however, overriden when values get above 1 billion. I noticed numbers got pretty large on Nightmare game modes and it started to cause problems in the UI where they got resized to unreadable fonts or simply went off-screen.

So large numbers will automatically be formatted whether you have the option on or off, and I have set it to be off by default.

This doesn’t apply to all numbers. Numbers that I know won’t get that high are still displayed as per normal. I can also set how many decimal places the number formatting can go for each text. EXP is typically displayed with two decimal points because I don’t restrict its values.

The End-game Turret


I actually called it the Hybernium Turret. Not really liking the name but it was a draft placeholder name that I got used to from very very early on in development after using it countless times.

I mentioned previously that it’s a one of a kind turret that only appears on the last map and has a unique method of attack. I really love this turret because it’s really unique.


The turret fires a destructive Arc at its enemy. When it does so, some sparks fly off from the center for visual effects. In the screenshot above, The main arc is black, while the secondary arcs are white.

There were some bugs, such as incorrect length of the arc when it shoots enemies. But I managed to shoot down the bugs one by one. Eventually, I also made the attack behave more like an electric arc – adding fading effects and locking onto an enemy before it fades.

It is also capable of unleashing a devastating attack.


Also, for added coolness, its information panel displays its damage as “???”. According to my math and the damage formula I set for it, it should 1 hit KO most monsters up till wave 80.

Why wave 80? Because that is the level of the final boss when he is introduced. I don’t want the turret to 1HKO the final boss’ summons. Having the damage be kept secret also makes this turret a little bit more mysterious. But I’m not sure if it will pander players not knowing what its true damage is.

The Final Boss

Fighting yourself?

Warlock - Copy.png

Nah, that would be too cliche. Throughout the game you keep hearing of the final boss, but you never actually get to see him until the final map.

This boss was extremely problematic to do because the final map has infinite waves. It is the first and only map to feature a survival mode. Unlike other maps where the superboss is spawned on the last wave, the conditions to spawn this final boss is different.

To spawn the final boss, you have to upgrade the Hybernium Turret to its max level.

Max Level!!!

This is the only turret in the game to be able to go up to Level 10 (other turrets cap at level 9).

At level 10, it goes destructo-mode and all the waves disappear, and leaves you with only one final wave:


The final boss spawns from a special spot on the map, the Mysterious Rune.Blog229.png

Speech Bubble?


The final boss is the only creep that has a ‘speech bubble’. Sort of. It can talk and the bubble also follows him around the map. There were two ways to go about it. Because text is classified as ‘UI’, they use screen space coordinates and uses a different camera to render.

Sprites like the enemies, my turrets and the map are actual world objects that occupy world space.

I initially attempted to make a Text Mesh. A Text Mesh does not require a UI Camera to render, so I am able to attach it to the enemy conveniently – it functions just like a 2D Sprite and I felt it was more intuitive that way.


Initially the text mesh appears blurry and I had problems with the sharpness of Text Meshes, but I eventually solved the blur issue.

But ultimately I did not use Text Meshes.

I went with UI Text, since that is what Text seems to be designed for. Using a Text mesh means that the text is at a constant fixed size, which normally isn’t a problem, but since my game allows you to zoom in and out, zooming out causes text to appear smaller. This is avoided if I simply use a UI Text.

This final map took me a long time to set up because of how differently it is made from normal maps. It’s not just the large map size, but also the turrets, enemies involved and the way the wave counter works. Special effects and conditions take a long time for me to add because the game doesn’t usually permit these sort of effects and I have to actually extend a lot of functions to make them work without hacks. So I hope it is worth all the effort.

I actually intend to do a proper ending to this game. The only other game I made that had proper endings and multiple endings was Introvert, a story-based game.

Multiple Endings

I was so intruiged and fascinated with the game’s story and possible endings that I decided to make the game have multiple endings:

  • Defeated (Bad Ending)
  • Victory without condition (Neutral Ending)
  • Victory with condition (Best Ending)

The outcomes of your final battle with the boss and the choices you make determines which ending you get. And yeah, the dialogue box does give you multiple options to choose from, which is very rare.


Oh, did I mention that you cannot quit or leave the battle when fighting the boss?

This message appears if you try to quit while fighting the boss

I think it really adds to the atmosphere. It is restrictive, so it only happens on the last wave. I don’t think it would be too bad. If you played up to the last wave and faced the last boss, I don’t think you would want to quit at that stage, right? The most likely option is if the player realises he is going to lose anyway, so he decides to restart the map, but realizes he has to wait for the boss to walk to the end and finish him. Hopefully this does not pander a lot – I actually need user feedback pertaining to this.



I have done a lot of fancy effects for cutscenes before, including lots of camera movement, parallax scrolling and animations. In this game, I just want something simple – 3 background art to illustrate the different endings.

Although I was supposed to only draw 3 large cutscene images, I ended up drawing 7. Well, at least that means it has a higher ratio of visuals to words for the ending. Here are the 3 original cutscenes:

A Mysterious Cube???


There was initially only planned to be one simple ending to the game, but I ended up adding a lot of special effects like a final superboss, a supermap and a superturret.

The originally ending was actually a pretty bleak ending. It was a bittersweet ending, but I later decided that the game should have one happy ending. Thus, I had hidden a somewhat secret ending in the game. It isn’t too hard to unlock it, but to view the ending you do have to satisfy two conditions. It’s not too hard (I could make it harder if I want to but there is no need to at the moment).


As you progress through the game, you start to find traces of a Mysterious Cube. This is a new object I added recently and is crucial to unlocking the ‘Happy Ending’.


Changes to the Booster Turrets

I changed the range formula for the booster turret and also, it now displays Grid Range rather than unit range, which can be a vague number to indicate the turret’s radius.


This is because the turret works differently (it does not shoot, it boosts nearby turrets). I also changed the way the RANGE UPGRADE skill affects this turret – it no longer affects. Instead, it receives a range boost from a separate skill, the ‘Advanced Boosters’ skill, which has other benefits as well.

Game Improvements

I’m starting to polish the game up in the event that it does get released. Not much to talk about. They are really simple things but it’s cumulation of stuff like that which make the game imperfect:

  • Story and info panels could popup mid-battle and obstruct the screen while action is going on behind, so they now auto-pause the game when triggered during battle
  • Centering of crooked / improperly-aligned UI

More Bug Fixes


Things like having negative health because I use rounding to integers (2.147b max value) start to appear and I also get tons of other issues as I test various aspects of mid to late game. I’m basically ironing out a lot of the bugs.

And draw order bugs…

At this stage, the game is unlikely to get any more new features or content, and I’m glad because developing any more new stuff is just going to add unnecessary complexity and also delay its release.

Balancing Tests


I’m now manually testing the last few stages of my game repeatedly. Trust me, it’s really very tiring. I would sometimes rather code and draw new stuff than test my game. And it’s not so much because the game is boring to play, but rather that I have to re-test the same level again and again until I get a good feeling about the difficulty.

With the addition of ‘recommended level’ displays. I also have to play the same map multiple times with different savefiles where my character is at different levels with different skill points, to get the MINIMUM level required to attempt that stage. Unfortunately, Math won’t help much with this type of balancing.

Last week, I had did the balancing up till Map 20. This week, I managed to balance Maps 21 to 29, leaving me to balance the last map on Normal Mode. Then comes balancing of the difficulty modes and the Challenge Maps.

Oh, and the game now has a big alien ship as a final boss on the ‘Area 52’ map I recently drew.


A Game is never done…


I think one thing I (and probably a lot of people) have to realise is that the process of making a game never really ends. Even when you release it, you want to always make it better – and I’m not talking about fixing bugs. I’m talking about adding features or content that players request for – to make the game better, increase its lifespan, etc.

When making this game I had to cut out a lot of ideas due to the lack of time, especially toward the end. Things in my ‘impossible’ scope truly never made it:

  • Character Equipment (I actually coded an inventory manager and boosting of hero stats if he wears equipment, but I don’t have time to implement).
  • Shop & Currency. I coded a simple shop in my previous game, IdleHeroes, and I could very well use some of its implementations here. In my design document, I drafted ‘Boss Tokens’ as a special rare currency from bosses that could be used to purchase powerful equipment to boost the hero, which is actually very under-used in the game. This feature is tied to the Equipment mechanic.
  • A Technology Laboratory with specific branched upgrades. Different research paths would give players customization over the turrets and add further strategic depth to the game.
  • Active skills. Abilities like casting a meteorite to damage creeps, summoning your own runes to battlefield(!), and increasing gold gain for short durations were very real ideas I drafted in my Impossible scope. I actually made my Rune script similar to turrets so that I can plant runes on the battlefield just like turrets. I have in the game a ‘discard-able’ UI which was reserved specifically for such features that would require an extended UI.

The list can go on really and I bet there will be players who when playing the game, would suggest/request the above feature(s) to be added.

Even for OldStory, the game I published earlier this year, I got messages and PMs from players asking me to add content – new classes, increased money cap, more stuff to do after 40 New Game Pluses (and boy I never expected people to play up till FORTY New Games). I was really happy to hear that. Well, point is, a game is hardly finished even as it is published.

But I’m glad that I was able to implement a lot of the things I set out to do and beyond that. And even without those features, the game already has quite a lot of content, more than the simple sandbox in my documented small scope.

Future Plans (Sidetrack)

After I am done with developing this game, it is likely I will spend the first few weeks of its release fixing any bugs that manage to slip past me (though I will try very hard to prevent this, I don’t have a lot of friends/testers, so it might be inevitable that some bugs will get through in my final testing phase), and also time will be spent updating the game based on user feedback.

But skipping past that, I would likely not have time to make another game of this scale, which is kind of sad. I even felt like making a sequel to this game to fix all the “issues” that the current game has but are too late to fix. There are a lot of things I wish I could do, that I wish I had the time for, but I don’t.

But if I am somehow able to squeeze time out of University life, there are 3 things I really want to do.

1. Continue making (smaller scaled) games

The first is to of course, create shorter, simpler games. I have been always working on seemingly bigger games than I can take on due to being very ambitious and how much I enjoy making games, but I would have to implement some kind of deadline so my passion doesn’t go out of control. But making games alone is truly a time sink. Unless I find a company/team or a group of people with the same common interests as I do, I think it would be best for me to restrict myself to ‘A Game in 14 Days’ kind of rule if I were to continue game development solo. Smaller games might be fun to make and it would be interesting to see what I can whip up in two weeks.

It’s also less risky and beneficial to players as well. If I make a game that is well-received by people and has generally favourable reviews with potential for expansion, I would focus more development time to update and improve it, and maybe even make a version 2. Whereas games with a design that isn’t as fun is best to be left behind and forgotten. I don’t want to waste peoples’ time playing a poorly designed game.

The only problem I guess is that unless the idea of the game is very strong, a game made in 14 days wouldn’t have much depth or features. It would expose me to developing games of different genres, but the output would be something pretty generic – I would be doing it more for the experience than the reward of having a polished, finalized game.


Enter a caption

On 25 January, I took a break from game development and I made my very first Flash Animation. I was inspired to learn flash animation because of two things I saw.

First, I had been to this place where I saw artists sketching out frame by frame animations. There was this animation of a character jumping from one hill to another. It was short but it sparked something deep within me – I wanted to be like them and do animations too!

Then, I saw a very cool looking 8 bit animation. It was similar to the way I animated sprites in Introvert and was something that looked like it belonged in an 8-bit game.

Feeling totally awed, I wanted to learn Flash animation. Sadly, I had no prior ‘training’ or ‘formal education’ in animations. I did have experience from sprites I drew for my games. But I felt very left out compared to those people I saw who had undergone such education and were steps ahead of me – people from design backgrounds, or art schools.

Nevertheless, I decided to do a stick figure fight.

My first attempt went really horrible – I tried bone animations but it felt very unnatural to me and tedious. I decided to go with the more hands on approach – literally using my hands to draw the stickman rather than using the mouse to construct and rotate its joints.

I started drawing stick figures, animating them walking frame by frame and to my surprise, I felt like I was actually doing quite well. It was my first time actually animating a stick figure. The frames were pretty smooth and it didn’t look too amateur-ish! I just drew one frame, then another, then another, and I hardly Ctrl+Z-ed. I was just so invested in drawing that hours passed without my knowledge.

It was such an exhilarating experience and I will never forget it – the bitter taste of my initial failure, followed by watching my 5-second long animation play out was second after second of pure joy.


3. Just drawing and drawing

Whenever I get very invested in developing games for weeks and months, I put off a lot of other tasks in my ever-growing TO-DO list.

Sticky Notes. They’re everywhere.

Depending on the colour of the sticky note, it could be a list of comics to draw, a list of games to play, a list of links to visit… They are basically everything I wanted to do but had to push off. When I have the time, I will be drawing more comics like I have always done, with more room and time for ideas and at a more leisurely pace. I will probably draw more miscellaneous inspirational backgrounds too since I sometimes find myself getting inspired really easily.


So what’s left? I think I actually am somewhat able to see the end of the tunnel. But it’s still very far. I also had a three day-long disruption because my computer could not start up and had to be sent for servicing. It just had to happen on a weekend too.

Content wise, I am left with the special effects of the Final Map and making the actual Endings.

Balancing wise, I have about two maps I have yet to balance. And I also have to ensure that Nightmare mode is not too difficult on the last few levels.

Other than that, the game is playable in all other aspects, and I am happy about that.


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