When I covered the Radius Pivot on LGR Oddware, I showed how games like Doom aren't designed for portrait mode. But then I said it would be dumb/fun if something like 'Tate Doom' actually existed, and WELP. Developer Matt Phillips took it upon himself to make that happen, and TOOM is the result! A vertical Doom conversion that runs in MS-DOS on original 486 PC hardware.
The performance issues are because I used the pure C version of the source without the assembly optimisations - might be trivial to re-add them if someone wanted to put the time into it (and fix a few UI issues, etc). I'd love to know if there's some kind of documentation for that mercury switch on the driver disks, I have ideas for how to make it switch orientation at runtime (I'd need a spare weekend and more beer...) Huge fan of the channel, and I'm glad this made your week