Thank you so much for the feedback!! Cumulative velocity is something I've done with so many other games and wouldn't be hard to implement. There's a small amount of velocity already in place, but it's capped so that nothing can move too fast. I totally get that the land collision is a bit wierd, wasn't quite sure how to make it feel like a crash. Sliding backwards is a great idea since the ships can only move forward they will eventually find the water again! The screen size is how it is unfortunately. I tried to make it go fullscreen, but I changed the settings and now I have no clue how to un-change them. High on my priority list though! Screen shake, sway, dynamics, and power-ups are all great ideas! (Perhaps if you ram another ship you have a chance of getting stuck on it and can push it into a debuff that way.) I will take them to heart and when I get back around to working on this I'll take another look at your comment and make updates accordingly.
Two controllers is a great idea! I used to have a friend who has a controller help test my 3d Pong game, but we went our seperate ways and now I only have one controller and a keyboard. If you want a game that has two controllers I'd recommend checking out 3d Pong.