Boss design principles

My last blog post showed a lot of the progress that’s happened with Malphas, the first boss for Super Space Galaxy. When I started making Malphas, I didn’t have much to go on for his design. Rather than copying anything else, I tried to draw on some of the principles I believed in for boss design. Hopefully these rules will be as much a discovery for you as they were for me!

Bosses must fight fair

A lot of games, mine included, let you venture into Hell or the netherworld and fight the most evil things the setting has to offer. I think this is implicitly the promise of a lot of games; however menacing the foe, it’s actually a fair fight and you can win. No matter how bad the situation seems, it is just a game. If the battle isn’t fair, the player might initially think that the boss is ‘hard’, but soon they’ll find that there’s no way to respond to the difficulty and the fight will become frustrating instead. That was how Malphas felt in the early stages.

As I experimented with him, I made a number of measures to ensure that Malphas fights fairly. At first his fireball appeared instantly in front of his mouth. This meant that if you happened to be around his mouth when he shot a fireball, you’d be hit with an un-dodgeable attack. The fix was to have a circle contract around his mouth to show that he was charging up an attack.

It might seem strange to think that the boss is fighting fair. After all, they’re supposed to be a demon who’s sincerely trying to kill you. I think it’s also important that they’re not perceived as holding back or artificially giving you a chance. Malphas is always trying his best to face towards your ship and shoot his fireballs.

Bosses must be interesting to fight

Fair is one thing, but the boss must also be fun to fight, too. Malphas’ one fireball was boring by itself. How to build on it?

Often, a second, contrasting attack makes for the perfect combination. The fireball is quite simple and moves in a straight line, forcing you to move around him. That’s why I added an 8-way projectile that shot in all directions to make moving around Malphas much more tricky. Now if you move too fast, you’re exposing yourself to more of the shots, but if you move too slow, Malphas will hit you with his big fireball.

I think it’s better to think in terms of incentives rather than just attacks. When I made these first two attacks, I made sure they represented very different incentives. This is a very common technique to make interesting gameplay. One incentive is normally too straightforward, but finding a balance between two can be exponentially more interesting.

Bosses must stay interesting

The combination of fireballs and the 8-way shot was interesting… for a while. If Malphas had only this one phase, though, he might be difficult, but he’d also be a very dull fight. My next idea was that he could switch between multiple phases with their own incentives. The switch from one incentive to the next would keep the fight interesting.

This has a lot to do with Malphas’ mouth. Normally, you should stay away from his mouth as it’s where his fireballs appear. His wing shots attack, though, gives you a reason to stay near his mouth or behind him, while projectiles appear along his wings. It’s a rather fun moment to realize that Malphas has finished shooting wing shots and you must now get away from his mouth.

I decided that Malphas should also get more difficult as you fought him. He goes through three damage stages, in addition to the ‘phases’ he cycles through over time. That gives him one variable that is out of your control, based on time, and one that’s in your control, based on how much damage you’ve done. The ramping up of difficulty also lets you learn Malphas’ moves in the early stages.

His second and third stages also include the ‘wind blades‘, which are designed to mix up the old patterns. They’re quite versatile and have 3 different formations. Which pattern you get also depends on what angle Malphas is facing relative to your position. Before I made the wind blades, I was left with a nagging feeling that Malphas’ attacks still needed an extra dash of complexity. If the wind blades did not exist, it would be necessary to invent them!

These boss-design principles also apply more broadly to making a good game. Your game must be fair, interesting, and stay interesting as it progresses. Giving a tug of more than one inventive at a time will make more interesting gameplay.

Almost everything I added to Malphas was essential to make a good boss fight. He has four different types of attack and three phases, but nothing has been added just for ‘fun’. So far Malphas doesn’t have any movement and there’s a few things to add, but he’s already a great boss battle. Expect to face him when I have the 4th demo ready!

Thanks for reading,

Kenneth Dunlop