A fair and scaleable spawn system was integral for Yamamura's replayability and proper difficulty scaling. We wanted the game to be accessible for an average person but also able to be mastered by gaming pros. We faced questions such as

• How long does the average game run?

• Will the game ever become impossible?

• How will enemy type spawn rates change?

We started at an arbitrary 5 minutes average match time for an average player. We decided to put a pin in this as a starting point. From there, I know I wanted the game to feel like it had waves.

Iteration 1 had all enemy types trying to spawn every few seconds. If successful, it was spawn an random number within a range. As time progressed, probabilities at spawn success as well as number ranges would raise. This was all balanced to make 5 minutes into the game very difficult.

This felt too random at best. Play testers described feeling that difficulty would jump around. After diagnosing, this was because of the range for the number of enemies that could spawn. Each enemy type would pick a random number from their own range. What if all enemy types picked the highest number in their range? This would be difficult. Then they might pick the lowest number the next wave. As the number of enemy types increased, this problem would only get worse.

Iteration 4 of the spawn system switched to what I called a "Dice System". Every wave, the game would roll a set amount of dice to determine what enemy type they would be. Each enemy type weight in this dice would adjust as time progressed. This means that number of enemies was a fixed progression no matter what the enemy type.

The 5th and final iteration added some small variability in number of enemies as well some enemy spawning outside of the wave system.

We had play testers play different variations of the spawn system without telling them the difference. We then asked them about difficulty. Play testers with iteration 5 had the most fun and felt the game was the most balanced.

While this is just a brief explanation of the spawn system journey, I learned a ton about balancing and system design through this task.