Overview
Ouroboros is the first proper boss fight in Strider (there was also a mini-boss style fight with an elite guard). It also was the capstone event of an early playable demo for the public at trade shows. As such, the team and I really wanted to make this fight something spectacular. Since it is the first boss fight, the player has very few unlocked abilities so the combat challenge would largely focus on basic navigation and basic attacks.
My design is structured as a three phase boss fight with transitions triggered when the player destroys weakpoint canisters attached to the Dragon's head. As such, at the start of each phase, the player is positioned at the tail and must travel to the head to destroy the objective.
Phase 1 - Vertical Climbing
The player climbs the dragon while it is vertically ascending
Along the body of the dragon, spikes emerge which electrify small sections of its body that the player must avoid. Players are encouraged to dash while climbing to avoid these.
The dragon itself alternates through several flight patterns which transition the player back and forth from vertical to horizontal/ceiling climbing
Phase 2 - Horizontal
After a cutscene, the dragon appears to dash forward, pushing the player back to its tail
The dragon then appears to fly through a swarm of drones. These are minimal threat and provide a method for players to regain some health when destroyed
The dragon again dashes forward, pushing the player to its tail again
Turrets spawn along the length of the Dragon's body that the player must avoid and/or destroy and occasionally an electrical charge travels down the length of the Dragon's body that must be jumped
Phase 3 - Horizontal with Hazards
After another cutscene, players are again pushed back to the Dragon's tail while a slew of missiles can be seen launching out of its body
A series of high-low missiles fly across the screen forcing players to navigate between them, after which the player is again pushed to the back of the dragon
The Dragon now begins to weave more forcefully like a sine wave, firing off homing missiles, spawning turrets, and flying by troop carriers that threaten to ram the player, creating a complex navigation challenge that is highly dynamic
Innovations
First and Only Climbable Boss
We were able to attach invisible, climbable objects to the skeleton of the Dragon allowing the player to climb it
While the initial setup of this went very well, we quickly discovered that due to how much the dragon articulates, we needed many objects which increased the risk of players falling off while tranistioning between objects. This required me to very carefully tune the size and position of these shapes to minimize this risk as much as possible
Faked Dragon Flight
Throughout the entire boss fight, the Dragon is completely stationary
All sense of motion is purely illusion achieved with a few techniques: having the background scroll, playing wind vfx, pushing the player by applying a velocity force, and having other objects fly past the Dragon
Given all these tools, it was my job to trigger them at the right moments to sell that illusion make the player feel the motion (fake as it was)
I was particularly happy with what I was able to achieve with the horizontal dashing that pushed the player back to its tail as a mid fight reset
Dynamic Flight Animations
I really wanted this fight to feel chaotic, like a wild animal trying to shake off an opponent. The fight duration was also going to be completely variable as some players would be able to beat it quickly while it may take several minutes or attempts for others, so the animation needed to be looped endlessly.
To achieve this, I designed a set of motion cards of how I wanted the dragon to move. Each card would always start and end with the same pose (per phase) so that they could be mixed and matched endlessly, but the path of motion would be different enough that players could easily notice the difference. Stair case left, right, up, down, oscillate, reverse direction, dodge 2 or 3 troop carriers, etc.
Giving these cards to my animator (John Behrns) gave him a foundation to author his work that met my needs for gameplay
Lessons Learned
Don't hold back on the first boss
First impressions really matter and a first boss fight is a perfect example of that. The player's experience there very well could be the difference between someone getting heavily invested in a game or just putting it down and walking away
This fight in particular was probably one of the most costly to develop BUT it was great spectacle that drew the player in. And it also ended up being a fantastic show piece for demos to get players interested in the game. Well worth the time invested.
Being explicit with what you need from animators
During early production on this fight, I gave my animator very loose direction on how I wanted the Dragon to fly. Fly this direction, weave back and forth, etc. Not surprisingly, neither of us were happy with the results.
When I sat down and explicitly drew out the path of flight I wanted on index cards is when everything really started to click. I quickly got an understand of just how much variation I could squeeze out of the flight, what motion would make for good moments of exciting motion, and just what was really not going to work. My animator was also able to very quickly churn out the animation because he knew exactly what I wanted.
While I always want animators to be a part of the process of inventing and defining character motion, this particular experience really taught me how important designing a strong foundation for the animations can be. Great animators will still be able to innovate within the foundation, but ensuring that they are well informed on the needs of the gameplay is always going to be
Better integrate new player abilities in to fight (Could do better)
While the player could use the charged slash or slide ability, I didn't demand that they use them in this fight or give them a noticeable enough reason to use them which is a bit of a miss.
Particularly for this style of game, giving the player the room to use that shiny new toy/ability can be a great feeling of accomplishment as well as a learning experience.