Deux Ex. I could spend hours on the same level just trying different solutions.

A game released in the last 6 months and that could be long enough to last for months?

I can't believe nobody said The Witcher 2 Enhanced Edition (released on April 17 2012, http://www.gog.com/gamecard/the_witcher_2). That would be the game I would buy (but I'm still playing the first game).

this is really easy for me. I'd play pharaoh. I mean I played it with only a couple other games (literally) for 3 years, on my old computer, when I was in highschool, why would I give up suck an awesome game, especially one I can get lost in and strategist in.

System Shock 2, lol.

Wing Commander 4

I do not remember if Zeus suffers from this drawback, but if Pharaoh is certainly a very long game, it is also a highly repetitive game. When you spent more time building your pyramid, importing stones one by one, than building your city, the interest is reduced. Especially when you realise that a bug will not let you finish the pyramid and that you have to start the mission all over again.

However, it remains a good game

Rollercoaster Tycoon 2, but I'm uncertain when it was released.

Deus Ex. No wait, Fallout 1... Or Freespace 2... or...

Good thing I can buy as many as I want.

there is a save function in a form of a code which you input to get straight to the last level you played (if you got the code)

Either Plainscape Torment or Ultima 7, although Ultima 7 is grate and is two games.

Last six months: Alan Wake, Deus Ex, Witcher 2 EE.

If you're flexible about the six months bit, the single biggest time-waster I've ever encountered is Arma: Cold War Assault. Between the campaigns, toying around with the map editor, and the bazillion mods - including massive overhauls like Finnish Defense Forces - ...well, I'd better not count up how many hundreds of hours of life it has cost me.

I'd need to see a list of all the games from the last 6 months, but from the top of my head, any Sid Meier game...probably Alpha Centauri, even though I have much fonder memories of Colonization.

Jagged Alliance 2, I could play that game on, pretty much, a monthly basis for a decade and not get bored of it.

Oh wait, already done that :D

zeus

Space Rangers 2(reboot) or MoO2.