Thanks Mindless. Grabbed the source and compiling now.
For reference, I like Tundra because it retains one thing that Lemmini left out: blocker behaviour (falling Lemmings don't turn around when they land directly on a blocker).
And Lemmix is out of the question, I run a Mac, and Lemmix doesn't play nice with Darwine.
And don't even get me started on Pingus...