Hi! Love the game, i've been playing for a couple days (it's actually the reason i made an account here on site!)
So first suggestion, i think a creature gallery would be really cool, the designs for your game are just awesome and i would love to just look at the different parts of the zooids, maybe even adding an in game camera so that people can share images of ther builds without having to use their computer screen cap function while avoiding enemy sipho guys. Maybe bind it to an out of the way key like C, at first. It would be cool to look at a player gallery of different siphonophore creatures.
My second suggestion would be a sand-box, "test" mode, kind of like a larger, multi area version of the species select screen. The reason for having this would be to get a good understanding of the movement mechanics as you add mover parts and more bulk, as well as maneuvering through spiky rocks. It would give you infinite energy to build up the zooid so you could play around with configurations, and maybe allow for a selection of enemy arrangements to test combat part configurations. It would have been good to know, for example, that if i arrange spikes on an intersecting path, that they would short each other out as though they had hit a rock wall.
My last suggestion would be to nerf the second boss a touch. I dont know if it's as strong as it is because this is alpha or because you want to limit play until you guys can make a finished game and charge for more gradual skill level play, but the second, purple boss with the poison mines and the array of flak throwers is kind of super difficult, because even with perfect timing on the player's part it manages to shove the player around effprtlessly, move them into position and then blast them into the stone age, assuming they can get past the purple poison mines. The only way i was even able to get close to beating that boss is using flak throwers myself to blast away the mines, only to get shredded by a wall of flak throwers myself. To remedy this, i would actually just cut the number of combat parts that boss has in half, and bunch up it's mid section in order to maintain it's defense of it's head part. It wouldn't completely remove that boss's combat power but it would allow the player to have a better chance to get in there and have a chance to hit it in a meaningful way. Another option is to choose one weapon or the other and replace the one not chosen with the chosen combat part, and then knock a third of the parts off and spread those parts on the boss to keep it from just being instant death. The players will still get pushed around allot because the thing will still have obscene mass, but if the player carefully maneuvers they would be able to suceed and it wouldn't feel like such a screw-job. I haven't even seen the other bosses so i don't know if they get even more over powered, but judging from the fact that on of the threads here are "screw the third boss"...
On an aside, I'm still trying to fix my downloaded version and have been playing in-browser for the last couple days. I know the problem (it's mentioned in the bug section by another user, black screen but the menus work and are visible, some part of code is getting deleted instead of integrated, i just need to figure out how to access it.) and i'll see if i cant fix it on my own, but it would be nice if an update could fix that problem so a player didn't have to.
The game looks great though, i really dig the way it looks and plays! The concept is super cool too, i like the whole idea of playing as a colony organism. Your doing great, don't give up on improving!