Supported this early on so I got what I got for pretty cheap but it's been in limbo for a long time now and so I don't think it's rude to recommend another project that seems slightly less in limbo but for 1/4th-1/2 the price called Smack Studio. This app is more PICO-like while Smack Studio is just a pixel editor with some neat rigging and rotation features. In my own bored journey I've moved past both apps to slicing SDFs in plugins like Mudbun or Clayxels. That way you can just render a 3D object and assign 2D sprites to points in your 3D graph and render them Daggerfall or Mario Kart style depending on the angle you're looking at them. Theoretically you could do way more angles than either of these programs support out of the box. We're talking about buying abandonware here cause it has its usefulness (try it on steam, return it if you don't like it). Smack Studio isn't abandonware and Mudbun and Clayxels are professional rendering plugins.
Smack Studio - A sandbox fighting game
It appears to also be a game, but you can use it similar to this program, I guess.