For those that like Diablo-esque hack'n'slash dungeon RPG games, Din's Curse might be of interest, especially as it supports co-operative multiplayer:

In Din's Curse, you will explore an extensive underground, slaying dangerous monsters, solving dynamic quests, dodging deadly traps, and in your spare time, plundering loot. Quell uprisings, flush out traitors, kill assassins, cure plagues, purge curses, end wars, and complete other dangerous quests or the danger WILL escalate. Not all is as it seems though, traitors will gladly stab you in the back, renegades can revolt against the town, spies can set up ambushes, and items might even curse or possess your friends.

Our game page has more information and screenshots. A demo has been released and you can now take this title for a test toast - both Windows and Mac OS X versions are available.

is it intentionally meant to look like it was made in the 90's?

It is a budget title so I suspect the focus is more on gameplay than having the latest flashy graphics.

haha the game looks worse than Diablo 1.

It's 'New retro'.

Many hybrid classes to experience - 6 full classes

Woah woah woah... FULL classes? Holy s***!