Vanilla Doom can only take skies that are 128px vertically. Horizontally is another story, as I've seen textures go as far as 1024, which is probably the limit. In case you want a sky that wide, you'll need to cut it up in 256px wide pieces, and piece them together in Slade. For this I'll just use TNT's episode 1 sky, consisting of 4 individual textures: DOEDAY, DONDAY, DOWDAY and DOSDAY, placed from left to right in that exact order, to replace Doom 2's first episode sky. In case you're using y