Strategy games like civilization, business sims and build-up-sims like Caesar (1+2+3, WOW these are GREAT games!), Pharaoh... were the first games i ever played and really liked. There are a lot of really great games from the pre-2000 era. Some of the greatest games of all times are fugglers2 and Gloriana I. Oh and Patrician 2 Gold (I think they called it Patrician 3 in the English-speaking world). Three splendid middle age business/trading sims. Build up a trading empire, get rich, famous, and important.
I also played The Guild Gold, also a great game. Basically the same concept like fugglers2 - produce wares and sell them for profit, and then become famous and important, get major, etc. But not thaaaaaat good. It gets old after a time. Patrician2 rarely gets old, and Caesar3 and Pharaoh will never get old
Only later i discovered RPGs... it all began with Diablo 2, which i played at a friends' house. Then i bought Diablo 1 (which is better than number 2 in my opinion, it is more "random" than the second one)... and soon i had Neverwinter Nights (D&D), Neverwinter Nights 2 (not so good as the first game actually)... i even once played a bit of Baldurs Gate 2, but the game takes really long to begin... My sister likes Hack-And-Slash stuff, i like the more tactical ones like Neverwinter Nights 1+2, and Baldurs Gate. You can pause the game anytime and plan your next moves. In some of them you have to coordinate a whole party.
Oh and i also have Rollercoaster Tycoon, Industriegigant, Airline Tycoon, etc.... and don't get me started with Transport Tycoon - so cool this game! There is OpenTTD - a free remake that works on windows, with extra stuff like trams. There are many many great games out there.
Civ4 is a great game - and MoO2 (Master of Orion) is also very cool. It is a turnbased Space E4 (explore, expand, exploit, exterminate) game like Civilization. The really cool thing is that you can create your own species, with bonuses in science, production, growth, etc.
I like more the citybuilding sims which have a lot of detail and compexity - Simcity 2000 is not complex enough, Caesar 2+3 and Pharaoh are. You need to plan very carefully or you won't reach the highest rate for your buildings. Oh and you also need to trade stuff with other cities to get money.
I also LOVE old-school RPGs like Final Fantasy with their great tactical battles. (FF6 forever !!!) Can spend a LONG time with those tactical fights! I once dug up a fanmade ZELDA RPG with great story. The guy used the models from Ocarina of Time and put them into the games in the fight scenes. It was one of the best games i have ever played.
Final Fantasy - Endless Nova is also a great fanmade game. It is not that long as you originally think. You think it really just starts when it is at the end....
The fanmade Legend of Zelda game is very different - you think it is done, but it really just BEGINS. Sadly there were a lot of bugs in the game that often made it unplayable. (Crashing bugs....

I never got through the whole game because of them.)
Gothic 1+2 (+Night of the Raven) are cool too... Gothic3 is a bit meh, and i haven't played Arcania, but i don't think i have to. It's no Gothic anymore.
I "recently" (1 year ago

) bought Spellforce Platinum - Nice game. It alternates between RPG-Quest areas and Realtime-Strategy gaming.
I have also banned myself from playing games like WoW... for similar reasons like your housemate

Too time-consuming.