An extremely challenging game, I hope that the final product will have a campaign mode of sorts which will allow for more creative play. The survival maps become extremely difficult as the enemies are relentless, group up and most times seem to be able to break you out of assimilate, making it really difficult to get back health.
I do see huge potential in the stealth map, it feels a lot more like what the game could be and used more of the mechanics (although I found Impale to be only partly reliable). I think a combination of stealth based gameplay with the combat coming in could be the best path, it would also be nicer if it was easier to "lose" guards instead of having to run all the way back to the start, fight one or two, and the stalk my way back just incase someone got lost. Saw a bug in the stealth level where some enemies would get trapped staring at a wall, and one ended up standing still and looking around.
I look forward to seeing more!