Hmm, since you've now bolded the "besides RPGs" bit, it seems I finally have the chance I've been waiting for... since I joined these forums really. What follows is a relatively short long fanboy tangent about a game I really like. Be warned, for gushing will ensue.
If you like RTS games...
Get Homeworld. NOW.
IMO, Homeworld is the best game ever made. It's brilliant in pretty much all respects. The gameplay is in full 3D, in space - and this is done simply enough that it's possible to learn it really quickly unless you're the kind of guy who gets confused in buildings with more than one floor. Furthermore, it simplifies the gameplay of general RTSs while keeping it challenging - as an example, it's the only RTS I've seen where your units will acknowledge they've been assigned to groups )pressing CTRL+1 to put things in Group 1 will not only result in them saying "Group 1, reporting" or some variation when you select them, but Fleet Command will provide you with constant updates on their status i.e "Group 1 is under attack", "group 1 reports victory" etc. Also, you can make groups within groups - call your whole strike fleet group 10 (done by pressing CTRL+0) and group all the fighters in Group 1, all the capital ships in Group 2 etc., allowing you to effectively micromanage without the irritation that usually accompanies RTS games in tense, action-filled moments. And finally, holding down CTRL and dragging a box around enemy units means you attack all of those enemy units).
The graphics, despite now being 11 years old (that's right, 1999 baby), are utterly beautiful - especially when you look at the backgrounds to most of the levels beyond the first 3, which are like playing inside a 3D painting masterpiece. Sometimes, when the fighting's done and you are left harvesting the remaining resources on the level (which can admittedly take a long time - one of the only criticisms I have for this piece of artwork), you find yourself just gawping at the backgrounds, lost in the wonder of how beautiful and colourful space is (and the atmospheric soundtrack - which we'll come onto - provides the perfect accompaniment).
The story is simple, but effective - it's not overrun with half-developed characters and MacGuffins, which are the kind of things RTS games shouldn't have. It focuses not on one guy, but on the plight of your faction as a whole as they travel through space. On top of this, said story is told with such atmosphere and emotion, that I'd say it's the most compelling story I've ever played through.
Then there's the soundtrack... oh lord. Oh lord, the soundtrack is the most beautiful thing ever composed for any videogame, ever. And this isn't even including the beautiful rendition of Agnus Dei that serves as its main theme. One of the pieces included is, I think, the single most atmospheric background theme tune you'll ever hear (you hear it in a nebula, you'll know what I mean when you do).
Even the voice acting is pretty good - it seems pretty emotionless when you first hear it, but it really grows on you.
Screw it, even if you don't like RTS games, you have to get this game. It plays very differently to your normal RTS, and I find myself returning to it much more often than I do to other RTS games like AoEII: AoK and Dawn of War.
Oh, and as to how long it'll keep you occupied? Well, an important thing you should know about the game is that it is very difficult. Another minor criticism I have of it is that the difficulty curve is more like a cliff - it's relatively easy for the first three missions, but you'll find yourself getting your ass repeatedly handed to you on a silver platter on every mission from the fourth onwards. Hell, even with the walkthroughs that I found downright necessary to complete the game with, you'll still get your arse kicked. The enemy AI is pretty good, as far as it goes - certainly good enough to catch the unwary off guard.
There's also some replay value in that there are multiple strategies you can use to complete the game - one thing I forgot to mention is that Homeworld has a persistent fleet, so units and resources you build in one mission carry over to the next in the linear plot (And no, linear =/= bad). Come to think of it, this leads me onto some advice - save all the time. Sometimes, you will find that if you completed one mission with only a couple of ships left and no RUs, you will be unable to complete the rest of the game, so you'll have to do that mission over from the point it started to go wrong. Come to think of it, this is another minor flaw - but it can be overcome through use of walkthroughs and repeated saving, so don't worry.
Hell, if you tire of the singleplayer campaign, you can always skirmish against the capable AI, or get Gameranger and play online (sadly WON support was retracted, so downloading Gameranger is the only way). The online community is small, but there'll typically be several games a day. Word of warning: Campaign and multi are different beasts, practice on skirmish first.
Phew. That was more words than I'm used to. Now that my blatant attempt to sell a game I'm a rampant fanboy over is done with, I've got to retreat away from the computer and into real-life-land. But take my advice, seriously. You won't be disappointed.
Just what I was thinking...
