Tiled is a tilemap or tile-based level editor. It's free and open source software licensed under the GPL-2.

For those into the Rust ecosystem, there's the Bevy Engine, which is an in-development 3D engine written entirely in Rust

collections of computer game assets go here

I worked on a sorta unique tool for a long time (sure doesn't look like it though because I rewrote it from scratch twice in the process!) Would like to post here, there is a free version with no time or content restrictions and a paid version that just has more features, but I'm afraid it could come across as advertising if I post. What would be your stance on it?