It's definitely a different game, since I have the source for Pebbles
However it looks like Dave has lifted the gfx from this game as a placeholder, until he could get one of the artists to commit to doing new stuff.
That probably explains why it was left in stasis, never released - he didn't have any graphics.
I think maybe the reason the 'source build' doesn't run properly is because it's assuming you want to load and edit a world or map, and I haven't quite figured that out yet so it's trying to launch an empty map. When I get a bit more time I'll have a more serious attempt at making it work.