Well, in an effort to keep it fairly simple and easy for the player, you (micdoodle) made the vacuum logic amazingly unrealistic. And also in the Yogcast vids, you could place water on Mars, which only has 1% the pressure and atmosphere of Earth. So, I propose you make it much more realistic. Water will instantly freeze on the moon when place and not contained, will evaporate instantly on Venus, and either freeze or evaporate on Mars or Mercury depending on the time of day. (both reach into the deep negatives at night) Also, up the death speed when not wearing your helmet to like 20 seconds. And a total renovation to the running out of oxygen (or not wearing oxygen gear), keep the chocking damage the same speed, but make it so you pass out because, realistically, you'd fairly soon be breathing in only CO2. So, you'd be like at half health and then you'd having your screen slowly, partially fade off (which your walkspeed lessens during) and then abruptly come back a few times and then finally you have the full sleep fade and you get game over. Each almost-passing-out should have a five second or more gap between them. And give the player some time to refill their tanks before they start drifting off. Make it seem more like the actual brutally hostile environment space really is.