There are a few I haven't put on this list, but it could be boiled down to this:
Oblivion
Half Life 2: Episode 2
Dwarf Fortress
Oblivion is by far my favorite game of all time. With it + Shivering Isles, I put at least 250 hours into it between 2006 and 2008. I'm now planning on playing through Morrowind, and possibly Oblivion again (with mods, however; I played it on the 360 the first times through).
HL2: Ep 2 is just amazing. I loved HL2, but this took it to a whole new level. It was beautiful without sacrificing performance, and the story left me craving the next installment.
Dwarf Fortress is pure procedurally-generated Fun, nuff said.
Some of my all time favorites, no particular order:
Dragon Warrior IV
Phantasy Star I, II and IV
Baldur's Gate (both)
Sim City (all of them, except for the non-Maxis one)
Civilization II
Duke Nukem 3D
Super Mario Bros. 3
Championship Manager 01/02
Contra
Morrowind
GTA Vice City
I used to love Intellivision. I had Burger Time, but my favorite has always been Shark Shark! It's too bad my Intellivision broke when I was still a kid (my Atari 2600 still works, though).
My system is still functional... pretty beat up though. I have about 40 games or so, most of the sports games that were available, but burger time was fantastic... right next to Nightstalker and Dungeons and Dragons. The bad thing was getting Intellivision thumb (before nintendo thumb)... I had blisters from some of the games like astrosmash.
If I had to choose for the systems I currently have working:
Pong: ...Pong
Intellivision: Burger Time
Nintendo: Mario Bros. 3 or Zelda...
Sega: Shining Force 2
Sega Saturn: Dragon Force
Game Gear: Shining Force
32X: Star Wars
Playstation 1: Xenogears/FFVIII
Playstation 2: Xenosaga I
Xbox: Star Wars Battlefront
Xbox 360: Oblivion or Bad Company 2 (depending if BC2 is glitched)
PSP: Silent Hill Origins
PC: Medievel Total War
AoE is kind of dumb...in order to "balance" it they just made everyone the same sans one unique unit that is only slightly better than the normal unit.
All units are indeed the same in AoE but it all depends on how much research has gone into your civilization...
Research is what fuels the betterment of the society.
Also, IIRC there are different units. I recall having a "canon tower" as the Chinese once.
And different units go well with different nations. When playing as the Mongols or Huns, for example, I would only use knights, horseback-archers (whatever they were called) and the special unit for the Mongols or Huns; the Mongols had a variation of the horse-archer-thing and the Huns had a guy on a horse with a torch (to burn buildings). It fit better with history.
--Really good AI (necessity, as there's no multiplayer)
--Near-infinite customization, from civilizations to your ships
--Excellently written backstory