So I realise I’m basically new to this place, but I imagine I can still put down a suggestion. XD So, here’s one: Moraff’s World. It’s a dungeon crawl game which can be kind of daunting, but boasts some interesting features, such as having a pseudo-3D overworld (kind of), a HUGE selection of spells, and I believe it’s one of the earliest games to support resolutions of 1024x768x256c. (And DOSBox is able to emulate a video card which it supports; the Tseng 3000!)
I’ve spent a LOT of time playing this and its sequel, Dungeons of the Unforgiven, as a kid. It starts kind of difficult, and gets outright brutal by the end, but I’ll occasionally go back and play it for a while.
Screenshots can be found here: https://www.mobygames.com/game/dos/moraffs-world
Shareware version here: https://www.classicdosgames.com/game/Moraff’s_World.html