Museum obtains rare demo of id Software's Super Mario Bros. 3 PC

1990 demo was rejected by Nintendo but led to id's own Commander Keen.

Super Mario Bros. 3 PC demo found by New York museum

id Software 'Super Mario Bros. 3' PC Port Rediscovered

Museum obtains rare demo of id Software's Super Mario Bros. 3 PC port

Super Mario Bros. 3 PC port by Doom creator id Software recovered by museum

Retro - Museum obtains rare demo of id Software's Super Mario Bros. 3 PC port, 1990 demo was rejected by Nintendo but led to id's own Commander Keen

Break the Con Down: - The NES Page

I found something hidden behind a bird in Super Mario 3D World + Bowser's Fury. Little idea as to what it could be : r/oddheader

35 years later, Mario 3 still does some things better than every Mario since

Id Software's demo for Mario 3 on PC is now in a museum

Super Mario Bros. 3 - Wikipedia

Mario is Missing! - Super Mario Wiki, the Mario encyclopedia

Thirty Years On, Super Mario Bros. 3 Remains 2D Mario's Pinnacle