I just played Chip's Challenge. Not the whole thing, I got stuck on level 9 so I quit. But there's just somet hings that Chip's Challenge will have that UUU won't. Like the mud blocks that turn solid when water touches them. And perhaps even water. I've got about 39% room left in bank 0 (the game's logic bank). I guess if I need to I could put the title screen in a different bank, but I don't want to.

I added keys, though.

You can't go to the keyhole square unless you have the key. I also made some small changes, like Ulysses's animation will not happen unless you are actually moving.

So enemies moving around, keys on some levels, stuff to collect, this is actually turning into a game IMO. What I need now is more than just 4 levels. I added a third level last night because I couldn't sleep. And I finally got to sleep at about 3 a.m. And I woke up at 1 p.m. I think I'll change level 4 a little more though, to make it harder.