This is a difficult one for sure!
I don't think I could have an overall favourite game, but I have three games that are of importance to me for varying reasons.
1) Counter-Strike 1.6
- This was the game that really started it all off for me in terms of gaming as a passion and gaming as a social item. I still vividly remember the first time I ever played it. My best friend brought me to a hole-in-the-wall internet cafe and introduced me to CS. From then on, for a few years, we would visit different internet/gaming cafes on the weekends for hours and hours and play CS and eventually other games. Man, I miss the days of internet/gaming cafes.
2) Perfect Dark for the N64
- This was one of the first games I ever played through to completion and repeated. It was a challenging game for me, and one that I got really excited about picking up and playing. When I finally beat it, I can recall the sense of accomplishment that it gave me. The thing is, I don't want to go back and play it again - because I'm afraid of changing the fantastic memories of it.
3) Silkroad Online
- This was the first true MMO that I played, and boy did I play it. I became enthraled in this game for a number of years and would go on to lead guilds and server alliances. I became friends with one of the GMs and worked on PTR testing before PTRs really became a thing. I had so much fun in this game, made so many friends and built a huge community - of which, some people I still keep in contact. The game itself unfortunately has met its ruin (although still active) through rampant botting and lack of response from the Game Devs. However, if you look for private servers, there are many out there with great communities.
All time, probably StarCraft.
But really, there are plenty of games I'd call my favorite at one time or another! Street Fighter and Mortal Kombat series, Marvel Vs Capcom, Thief, Need for Speed, Mario Kart, Contra, Ninja Gaiden
NR2003 racing. The reason I started building serious machines. Microsoft wheel and pedals were gold in those days but I bought them. Enjoyed thousands of hours and several years of competitive racing.