As others have already mentioned, Divine Divinity is only comparable to Diablo based on the isometric view and the combat mechanics. The core of the game, though, is reminiscent of Elder Scrolls games : a huge open world, tons of (actually interesting and innovative) sidequests and a complex but simple to manage character development. Graphically, it is perhaps not stellarly great (although the lizard jokey really looks cool :), but it's more than adequate, with only the occasional isometric view specific problems creeping up (objects or NPCs blocking the view on loot, difficulties visualizing different levels of terrain or high objects like columns and trees). The game is so engrossing that those details can easily be ignored. Soundwise, on the other hand, it is just great The sound effects are all very well done, the (sparse) spoken dialogue is not perfect but fits well in, and the soundtrack is a gem (and it's even included in the bonis :). It's really one of the best C-RPG soundtracks I know of, breaking with a lot of preconceived ideas what a medieval-fantasy game soundtrack should sound like. If you are into real time quest/story oriented RPGs, with quite a bit of hack'n slash and a lot of exploring, then you owe it to yourself to get it.
Arx Fatalis is a very atmospheric RPG, with interesting (and sometimes even funny) quests, likeable NPCs, a gesture recognition based casting system which makes magic much more involving (and during combat, frantic) matter than the standard"click on the right icon" scheme. Too bad Arkane Studio didn't use the same magic system when they did their following game ( Dark Messiah) to completement the physical combat. I remember reading an interview with the makers who said they were inspired by the two Ultima Underworld, and it shows in a very good way. Graphically the character models are a bit on the very low polygon side but that doesn't hamper the fun. The one RPG players I wouldn't recommend this game to are those with claustrophobic tendencies : you REALLY never get outside. For all others : it's a must-have!
I'm normally not into RTS's. I loved "Z" (from the Bitmap Brothers) when it came out, and the Myth serie, but I can't wrap my mind around micromanaging ressources and units. Nevertheless I bought Total Annihilation here after reading a few reviews and I fell in love. It's all pretty straight forward in terms of ressource managements : build energy collectors, ressource storage enhancements, watch your supply plies grow without any further ~work~. The mobile units are similarly easy to handle, have relatively fine grained controls and an adequate AI and pathfinding which means you don't have to constantly control whether units are blocked somewhere or are attacking single handedly massive opposing forces. graphics and sound are a bit dated (especially the cheesy voice-over in the campaigns ;) but it doesn't hamper the really great gameplay. As someone else stated : unless you're absolutely completely turned off by RTS's this game is worth buying. For an RTS, it's nearly ~relaxing~ and it's pure fun.
