Watch Highlight: Doom Mod Research Night from TekAdvisor on www.twitch.tv
If the original Doom is too Oldschool for you; Zion brings several of Doom 2016's visual, musical and gameplay elements to the GZDoom engine. It's still in development, but it's already quite promising.
Watch Highlight: Smooth Doom from TekAdvisor on www.twitch.tv
Doom's not exactly known for subtlety, but the animations can definitely be upgraded without altering the gameplay.
Official Page, including downloads for accompanying texture and sound effects add-ons
Watch Highlight: Doom Neural Upscale from TekAdvisor on www.twitch.tv
And if Doom's low-resolution textures hinder your appreciation of this classic; an AI went through the process of upscaling the graphics. Plutonia Experiment might not have been the best iWAD to test it on, however.
Official...