This is excellent. One of my favorite entry for sure. Pressing space and making them all spawn is so satisfying. The graphics and sounds are simple but they work really well.
The only thing is that I had to press every key to find out that "N" gets you to the next level. Other than that, it's perfect.
Thanks! If I finish the game I'll add more prompts (like for n for next level). I also love making them all rush out rapidly - I'd like to add some more sound effects reminiscent of the pitch increasing spawn noise from the original lemmings and maybe a way of killing them all off "oh noooo". Sound isn't really my forte but I'm sure I can come up with something that sounds fun and isn't too irritating :)