Yep, I've always wanted to play a faux retro Fallout platformer. Could be a Wizards & Warriors ROM hack with power armor instead of knight armor and ruined buildings instead of trees. Shishkebab blade instead of greatsword.
https://www.youtube.com/watch?v=VbIJM1xAjNY
Also, Faxanadu can be hacked for action role-playing Fallout. It's not difficult to adapt to the different setting. Both games have the mechanics to base an indie game on but you need a license from MS and it won't happen.
Then you have game companies saying unlicensed products stifle innovation, but old games redone differently are new content better than original and the only thing that's innovative to corporations are endless official sequels to milk franchise cash cows with.