I played the single player campaign twice through on release, but then Unreal came out just five months later and its campaign blew me away with its colored lighting, transparency, imaginative levels, better music, and so on. I have vague memories of coming back to Q2 after a couple months playing Unreal and finding it kinda dry and boring. I never really got into multiplayer, maybe only played half a dozen matches.
Then Half-Life came out in November... and Tribes in December of '98. What a time for gaming that was! *nostalgic sigh*