The work of modder Edy Pagaza, the Doom: Eternal Slayer mod adds a 3D player model with modern Doomguy's sword to classic Doom 2 so you can rip and tear up the old levels with something closer to the new game's combat.
The mod isn't finished yet, with more melee weapons and a collection of ranged weapons still to be added, but it is already playable. Seeing a rounded marine run through MAP01: Entryway carving up pixel imps is weird, although it pairs well with Andrew Hulshult's remake of the original music (opens in new tab).
You can download the current version of Doom: Eternal Slayer from ModDB (opens in new tab). According to the description, "this is the base of the mod. Also, will contain an exclusive boss fight with the marauder and icon of sin. But will take some time to release it."