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Balancing a two-hero battle system with Bossgame: The Final Boss Is My Heart

From boss design to controls, here's how developer Lily Valeen made the game's collaborative one-player combat work.

Joel Couture

November 22, 2022

8 Min Read

Bossgame: The Final Boss Is My Heart is all about a pair of girlfriends who hunt devils, battling through a barrage of boss battles whenever they’re not gently teasing each other through texts. Players will have to control both girlfriends at the same time if they’re going to overcome these nasty bosses. Teamwork is vital to a good couple, though!

Game Developer spoke with Lily Valeen, the developer, designer, and artist behind Bossgame, to chat about how controlling two characters both limited and opened up the design of the combat, how learning its systems can feel a bit like learning to play the drums and the thoughts that went into making the heroines feel genuine.

Game Developer: Bossgame is all about girlfriends beating up on horrible boss monsters. What inspired the concept for this game?

Lily Valeen: Going into Bossgame, I had three main goals:

"I want to make an action game that feels good to play on phones."

"I want to create the feeling of a classic RPG, but smaller and denser, so that people with full-time jobs can actually play it and I can actually finish it as a (mostly) solo gamedev."

"I want to tell a romantic story that explores an existing relationship, not a will-they-won't-they."

These were all challenges I set for myself, and they shaped the game! Bossgame is 100% bosses because I wanted to keep it dense and respect players' time while still reaching those emotional highs, and bosses are often the most interesting parts of RPGs. I wanted to write about girlfriends because love is so much more than the first kiss! And really, who doesn't feel like they've had to hunt devils just to make the rent?

What thoughts went into having the player control two characters at once? How did controlling two characters affect the design of the gameplay? The layout of the character attacks and abilities?

Controlling two characters at once was definitely the core that everything else grew around. Before Bossgame, I experimented with a first-person mobile game where you controlled your left and right hands to combine items. When I got invested in the romance story, I realized the two-hands mechanic fit perfectly for controlling two heroes! I also knew I didn't want to add any player movement because it's difficult to control accurately on phones. So instead, I added tension by having you juggle two characters attacking and defending in tandem, and I made the bosses very fluid to make up for Sophie and Anna being stationary.

From there, the layout almost decided itself. The buttons and UI moved to the sides of their respective characters, which means the only place for the boss was smack dab in the middle. The placement of backgrounds, the trajectories of attacks, and particle effects all landed where there was space remaining for them. A lot of Bossgame's design came from making the most out of the strict constraints of working on mobile. It forced me to consider every piece carefully, and the game came out better for it.

Two Hero Boss Battle

How did you balance the needs of two characters to keep them from overwhelming the player? How did you use the two characters to make things more exciting for the player?

I learned early on that complex abilities were hard to manage within the speed of the boss fights, so I made Sophie and Anna's skills straightforward (a fast attack, a powerful attack, and a shield) and nearly identical (though there are some unique exceptions). I also removed the concept of Hit Points entirely, instead focusing on a single energy meter that dictates a character's attacks and defense. All of this makes it so your thumbs can manage two characters at once. 

Despite having relatively simple controls, the two-character setup gave me a ton of opportunities to add unique things to the game, too. You can build and maintain combos by staggering each hero's attacks. The boss-stunning Love BREAKER requires you to charge and release Sophie and Anna simultaneously, which makes it feel cool to execute! And, of course, the two can revive each other. As long as one remains standing, you can recover, so it never feels hopeless!

With two characters, the bosses can get more interesting abilities too—feinting which character they'll attack, bouncing between characters during a combo, firing beams that sweep from left to right; I was able to make the whole screen feel like a battleground while still being easy enough to comprehend.

Boss Battle

The rhythm is important to the combat and feel of the game. How did you work the beat of the music into the movements and actions of combat?

So, while Bossgame is not a rhythm game, it certainly has a rhythmic feel. I think the controls are a part of this! Several playtesters commented that learning to play Bossgame feels like learning how to drum; two hands working in separate but coordinated rhythms. After a while, you learn how long it takes to charge an attack, and the timing becomes second nature: attack, attack, defend. The soundtrack helps with this—it's that kind of pumping dance cadence that loosens you up and gets you into a flow that matches the back-and-forth dancing of the battles. It doesn't hurt that RoccoW makes incredible music that makes you want to keep going just so you can hear more.

What do you feel makes for an interesting boss fight? How did you incorporate those feelings into Bossgame?

The most memorable bosses combine a few key elements: a unique flair and personality, emotional peaks, and mechanical mastery. But when your game is all bosses, it's hard for them to feel like bosses. So, I focused on giving each a distinct personality and weaving them directly into the story via the text cutscenes. You talk to every boss before you fight them, and each has a good reason to get in your way, which makes each fight feel more meaningful than just, like, a bigger dragon. Many of the bosses are introduced long before their fight, too, which creates a "Oh shit!" moment when they turn on you!

From a mechanical standpoint, I made sure each boss has a couple of "normal" attacks to apply pressure, a powerful attack to keep players on their toes, and a flashy attack to add to the hyped-up "anime" feeling of the game. It's just the right number of patterns for players to be able to learn, and it creates a nice tempo for the fights! Each battle starts relatively slowly and introduces you to the new patterns before building in pomp and intensity so that by the end, you're wiping sweat off your forehead. I also tried to make each boss' attacks match their personality, like Donovan summoning sacrificial henchmen to throw at you.

You included many difficulty options to let people tweak their experience. How did you decide the ways in which people could adjust the challenge level of the game?

I knew right away that Bossgame needed something akin to Celeste's Assist Mode. I figured players would want to see the story through, but I didn't want to force them to struggle if they hit a dead-end. With that in mind, I added a plethora of different options so people could experiment and find what works for them. So far, it seems like players are very capable of landing on "Ah, this is tricky, but not TOO tricky". Admittedly, some I added because it was pretty simple to code, like adjusting attack damage or adding invincibility. Autoblock took a bit more work, but it felt like one of the more interesting ways of changing the difficulty. It was also super convenient while testing and recording footage!

Basically, if I could add it and thought someone might use it, I did.

Text Exchange

A big appeal in the game is the loving, funny connection between the characters. How did you work to create a connection between the characters and the player so quickly? What ideas go into making us care for Sophie and Anna?

I think Sophie and Anna are easy to connect with because they're both total dorks. If they feel genuine, it's because they're not trying to be impressive snarky heroes. They're just trying to survive a crappy job with flirting and obnoxious jokes. We all do that, right? They tease each other a lot (like partners do), but they're also unabashedly kind to each other. They aren't perfect; they don't always speak up when they're upset, they make mistakes, argue, hurt each other.

I think players appreciate characters with relatable flaws and honest human emotions. I tried to consider "What would someone really say here?" even when it came to writing the bosses. I caught myself going, "Ah, this sounds like how my girlfriend and I talk, this is how my friends talk," a lot, which was super reassuring!

Part of the connection with the world and its characters comes from texting. What drew you to add this system? What do you feel it added to the player's experience of the game and its world?

The texting was such a fun device! It was a super convenient way to avoid more complex VN bursts, and it grounds the player in a modern setting (working a job, paying the rent) despite Bossgame's fantasy universe. It also creates a mysterious atmosphere... it's not really clear how much of the conversations take place via text or in-person, which leaves the door open for silly jokes and sudden curves. IMO, it's good when players are a little unsettled. Keep 'em guessing!

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