A few that come to mind for me are
- ASCII Sector - space roguelike that was released in the last 2000s
- Sonic Robo Blast 2 - free 3d sonic fangame, built using a Doom engine of all things…
- ClassiCube - free sandbox block-placing game that is similar to 2009/2010 Minecraft Classic
- Chronicles of Denzar - free browser-based RPG similar to dragon quest (previously PhantasyRPG.com) running since the early 2000’s
Seconding ASCII Sector as well. Basically Privateer’s Gemini Sector world with the gameplay expanded and of course ascii based and more rogue like. Tons of fun.