My wife and I absolutely love this game and we play it in cooperative mode. It’s fun and addicting. We have managed to do quite a lot than just me playing by myself.
I have a suggestion though. Most people now have multiple screens so if it were possible, I was hoping you’d add the functionality to be able to use a second screen for coop play. That way, we have more viewable area than on a split screen. Or maybe add a LAN coop so we can use each of our own PCs to play. Even though I have a large screen setup, it gets confusing sometimes.
Otherwise, good job on this game. I especially love that you allow the use of OpenGL for older machines.