Game Developer Deep Dives are an ongoing series with the goal of shedding light on specific design, art, or technical features within a video game in order to show how seemingly simple, fundamental design decisions aren't really that simple at all.

Earlier installments cover topics such as lessons learned from ten years of development with Ingress engineering director Michael Romero, how legendary Dwarf Fortress programmer Tarn Adams updated the game for its official Steam release, and how architect and solo developer Jack Strait made an entire horror game in PowerPoint.

In this edition, Modus Games project lead Rafael Gatti explains how his team found the overlap between the two wildly disparate game genres of rhythm and fighting, resulting in their unique game God of Rock. 

As designers and developers striving for innovation, mixing different genres has always been a bottomless source for new creative ideas. The blend can provide new takes on established formulas and push the industry forward. But innovation without a purpose is meaningless, a mere gimmick at the end of it. Having an end goal and a clear vision of what you intend to accomplish as an experience serves as a compass, guiding you through understanding what elements would best serve that result, and what makes them so great and genre-defining. A chef aiming to create a new dish wouldn’t just throw it out there that “it’ll be a Tex-Mex meets Brazilian barbecue dish;” they already have an idea of what they want to provide in terms of experience with that new plate, and that will be the driving force behind their pursuit. Our intention with this piece is not necessarily to present a recipe but our account of how we approached it.

Hi, I’m Rafael Gatti, project lead at Modus Games. In God of Rock, we already knew from the get-go that the game would be a mix of rhythm and fighting. Both genres have great communities, both are competitive and performance-driven, and in both, reaction time plays a huge role. But the similarities seem to end there. In rhythm games, performance and results are based on how well the player scores against the track. In fighting games, it’s all about how well you fare against your opponent. That’s just an example of a fundamental difference between such critical defining concepts in each genre: the winning condition.

We started out as a rhythm/fighting game blend, but with the idea that the fights would be in the same style as the more hectic ones in Dragon Ball Z. If both players kept up with a song’s note charts, they’d perform evenly matched, lightning-fast attacks that clash with one another in a huge display of power, tussling in a stalemate that looks and feels anything but stale. That functioned as our compass, our founding stone per se. At the same time, it also helped us define its pace, scope, and mechanics. As the characters were evenly matched, it’d all come down to a final blow that one of them would fail to defend. All elements of the game would revolve around that clash.

The concept doesn't play well in terms of movement and positioning, and could even disrupt the pacing. On the other hand, attacks are fundamental, the same way hitting notes is the basis of a rhythm game. That was the first connection, the first thing we established: by directly associating the attacks of each player’s character with the notes to keep in time, we established a bridge between core elements of the genres we blended. Since God of Rock’s battles are a continuous clash of attacks that players deploy simultaneously (as long as they’re on beat), it felt natural to make it so that players would be facing the same track, comparing their performance in a way where one missed key would translate to an attack that got through.

At this point in development, we had players facing each other and attacks that were tied to the beatmap and dealt damage, which in turn called for an HP bar. But they didn’t really feel like the players were fighting one another; in essence, they were still facing off against the track and comparing scores, and there wasn’t a lot of innovation in that iteration. It lacked the strategy and agency of fighting games. Those were the two elements that we felt would be a perfect match and would break the barrier of God of Rock being only a rhythm game, instead turning it into something a little bit different and more unique.

Agency is fundamental in fighting games and usually doesn’t have a lot of place in rhythm games. When it does, it still feels very constricted—players can perform certain types of actions but only during specific segments or timeframes, for example. We saw that as our window of opportunity; we wanted to design actions that players could perform at any time and affect their opponent. The end result is the special moves system we put in place for God of Rock. Players can perform special moves whenever they want during a match. These special moves will add a new sequence of notes in the opponent’s track, with the familiarity of using the same type of inputs as one would use in a fighting game (half-circle forward, for example) to execute a special move, as well as the skill needed for it, while also not compromising the beatmap inputs or adding a lot of complexity on top of it.

On top of providing agency, it also paved the way for us to develop the RPS/Reversal system and added effects for the special moves, adding a more strategic approach, as knowing when and what to use is key. Being a rhythm game, it opened opportunities for special moves to not only deal damage but affect the opponent in other ways, like altering their track, controls, or perception. And as a result, it gave us a reason to have a diverse cast of characters, each with their unique set of special moves, with a proper kit and a way to play it best.

There was just one thing missing to truly feel players were facing off through song. The focus needed to be on the battle; we couldn’t have songs finishing before one of the opponents was defeated. That’s where the concept of overtime and a looped segment entered the stage. Now matches only finish with a winner, and we also have control of that ‘stalemate’ scenario, making adjustments to each new loop to force one's hand, like a damage multiplier, for example.

This all constitutes the basis of our gameplay loop. Bear in mind that although this was presented as a linear series of ‘logical deductions,’ there was a lot of iteration for each step to reach the point where it felt best for the player. Some challenges included how to address asynchronous actions (like special moves) within the purely symmetrical system we had in place (all attacks/actions should have equivalent reactions as players were facing the same beatmap) and designing systems that reward skill and strategy but also have in place tools that a less skillful player can use to equal the playfield (as in having a different set of special moves work differently than EX and Ultras; or the dynamic difficulty change).

With the game now launched, the community can experience it for themselves and hopefully have as much fun as we did developing it. We’re thankful for the opportunity to create and work on this unique project, and hope it serves the community well, bringing a lot of excitement and some over-the-top duels! And who knows, maybe even help push new ideas or genres forward.