You're thinking too much about the core mechanic and not the game as a whole! Your enemies get increasingly more complex and difficult and the color design helps translate difficulty. I didn't get that far in your game cuz I'm really bad at it but I'd like to know some of the specifics of what your enemies do in later levels.
Thanks for the feedback! Here's all the stages:
Red Stage (Starting Stage): Is the first stage and introduces the red enemies (otherwise known as “Trackers”). They only follow the player and are the basis of every other enemy in the game.
Orange Stage (Requires 10 points or more): Introduces the orange enemies (otherwise known as “Shooters”). They only follow the player around and shoot at the player.
Yellow Stage (Requires 25 points or more): Introduces the yellow enemies (otherwise known as “Splitters”). They follow the player around but upon death, split into four smaller projectiles that travel in an up, down, left and right direction respectively.
Green Stage (Requires 40 points or more): Introduces the green enemies (otherwise known as “Seekers”). They follow the player around but upon death, release a projectile that homes in on the players location for a few seconds before dissipating
Blue Stage (Requires 60 points or more): Introduces the blue enemies (otherwise known as “Tanks”). They follow the player but unlike the rest of the enemies of the game, Tanks have two lives. When they spawn, they are dark blue in colour but once the player shoots them once, they dark blue shell is destroyed, and the actual enemy is revealed to be a smaller light blue enemy. The player can then shoot this light blue enemy to permanently kill them
Purple Stage (Requires 75 points or more): Introduces purple enemies (otherwise known as “Exploders”). They follow the player but after a small amount of time, will explode into 8 different projectiles that travel in 8 different directions. The player can stop exploders from exploding by shooting them before they
Rainbow Stage (Was not finished in time for game jam but will be released once the voting period is over. Requires 100 points or more): Essentially the game becomes more difficult. Red enemies continue the behave the way they have been, Orange enemies shoot a three bullet in different directions ( \|/ ), Yellow now have the chance to split into four projectiles that make an x and not a +, green now sends out multiple homing projectiles when they die, blue split into two instead of losing a life and purple essentially become atomic bombs that must be killed before they explode as their explosion is larger and the chances of surviving it with everything else going on is very small. Like the last stages, enemies are spawned in incrementally in stages (e.g. Rainbow Red, Rainbow Orange, Rainbow Yellow etc.). The player can tell what stage of rainbow stage their in as the player will gain rings similar to the logo of the game until they eventually become the logo (minus the text).
That's all the stages (implemented and planned)! I also have ideas for separate game modes ( Warp In The Chamber - teleport only, No Shot In The Chamber - no bullets but enemies can hurt each other, Explosive Chamber- bullet explodes and comes back to when you press space) but I still have to develop them a bit more. Thanks once again for the feedback!