The best is always saved for last, isn't it? Unfortunately, not in this case, as it looks like I'm the last one to present his Top 10 of this decade. Yes, I firmly believe that the 00s will end with the end of this year. I expect a lot of e-mails outlining your concern of my mental state regarding that statement.

Unlike my colleagues, brethren or what have you, my list is based on what I believe are outstanding achievements acquired by a genre or a series of games. If that makes sense. So, here goes nothing:
09. Call of Duty 2 (2005)
Topping Call of Duty couldn't have been an easy job, but Infinity Ward's bright minds and capable hands managed to give us an unparalleled WW2 gaming experience. Using scripted events rationally and with a sense for placement, Infinity Ward gave Call of Duty 2 a distinct movie feel that gamers simply love. Its multiplayer component still holds a special spot among competitive gaming communities and will no doubt live on long after the game's intended lifespan.
08. The Sims (2000)
Creating a game that will simulate human life is no easy task. As such, The Sims should stand for more than just an award-winning video game, it should also be considered as a huge achievement for the industry. Seriously, have you ever considered the scale of the project? Aside from raising the bar for simulation games, it also allowed kids with the Oedipus complex to fantasise about what lies underneath the blurry censoring on their virtual mothers. (That you even wrote the last half of that sentence speaks volumes - ed.)
07. Psychonauts (2006)
An underreated title, Double Fine's Psychonauts reintroduced the classic platforming genre to the sixth generation of consoles, and it did that in style. Filled with a ludicrous amount of timeless Tim Schafer jokes, Psychonauts offered an interesting storyline, cool game mechanics and a fresh, imaginitive art style. Needless to say, letting players explore levels inside of less-than-sane picturesque characters is what made fans crazy for Psychonauts.
06. Star Wars Jedi Knight Jedi Academy (2003)
I'm not here to argue about its place in the Star Wars Jedi Knight series of games, nor am I here to tell you about its great single-player campaign. Jedi Academy set itself apart from the rest because it was a very community-driven game. While Raven Software did a good job of creating a memorable Star Wars experience, the secret behind Jedi Academy's popularity lay in the Quake 4 engine on which it was based. Thanks to the engine's mod-friendly structure, everything was customisable with the right tools. This spawned clans, modding communities and, by extension, UFO as a gaming website. When it all comes together, Jedi Academy left a mark on gaming communities who, even though they do occasionally dabble in lightsabre tomfoolery, are still waiting on a game that is capable of taking its place.
05. Shattered Horizon (2009)
Only a small amount of developers have the right to say that they took part in reinventing a genre and Futuremark Games Studio are one of them. Shattered Horizon pushed the boundaries of conventional first person shooters, placing players into space and offering them complete freedom of movement. While it does take a toll on the average computer, one can't argue that it isn't a small price to pay for a breathaking and unique multiplayer experience.
04. Beyond Good & Evil (2003)
Despite being a practically flawless title, Beyond Good & Evil didn't sell well. Being shipped in the same boat Splinter Cell and Prince of Persia: The Sands of Time didn't exactly help it get noticed, so yes, it also suffered from a lack of marketing, but that didn't stop it from becoming a cult classic. Beyond Good & Evil offered a near-perfect blend of action-adventure and stealth. Its storyline was deep, talking of corruption, conspiracy and resistance movements, and its characters were more than a joy to interact with. Words aren't enough to describe the amount of polish this game has or how well it succeeds in exploring its characters as the story progresses, creating an utterly immersive and 100% amazing videogame.
03. Battlefield 2 (2002)
DICE knew they created a hit when they released Battlefield 1942, and its sequel did more than just build up on that succes. While its single-player campaign arguably left much to be desired, the multiplayer portion was undeniably where the game shined. Battlefield 2 introduced a chain-of-command system to multiplayer matches, offering commander, squad leader, squad member and soldier roles, each with their own appropriate voice communication. It took advantage of teamwork, dismissing the wolf style of play many were used to, and it proved that a decent strategy is more than enough to overpower any opponent.
02. Fahrenheit/Indigo Prophecy (2005)
No game was capable of evoking such a wide spectrum of emotions in a person as did Quantic Dream's Fahrenheit (or Indigo Prophecy in North America). With the help of a deep and enticing storyline, Fahrenheit manages to develop characters in such a believable way that one becomes familiar with the characters' fears and phobias. The game also brings the adventure game genre to a new level, offering a a very interactive gaming environment by introducing a mental health bar and some pretty amazing scripted quick time events. Fahrenheit is definitely one gem of a game.
01. Mass Effect (2008)
Bioware's Mass Effect is amazing. No one can deny that. I don't think I'm articulate enough to write about how good it is in complete sentences, so I'll just use a couple of words to express what I feel Mass Effect is: Immersive. Intelligent. Profound. Gratifying. Epic.