Bear Simulator - Bear Simulator is an Action-Adventure and Single-player Simulation by Farjay.
Crypt of the NecroDancer - Crypt of the NecroDancer is a Playable, Action-Adventure, Rough-like, Role-playing, Co-op, 2D and Single-player video game created and published by Brace Yourself Games.
Brain Simulator - Create your own AI Brain
Dungeons of Dredmor - Dungeons of Dredmor by Gaslamp Games
Streetmix - DIY urban planning
Moonlighter - Create some headspace & focus on building those ideas