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Very much enjoyed most of the games in the DC library, but only one game garnered over a thousand hours of my attention, Phantasy Star Online.

Jet Set Radioooo and Project Justice! Played Rival Schools in the arcade and the sequel does not disappoint!

Crazy Taxi for me. I loved everything about this game and have played it more than any other game. Got it when came out and it felt like the perfect game for a 16 year old from the attitude to the music. Also my favorite commercial for a DC game:

https://www.youtube.com/watch?v=WbXZQLjGqpo

Phantasy Star Online Ver. 2. The music, visual style, and gameplay have aged well and this game is still quite active online to this day thanks to private servers.

Honorable mentions: Marvel VS Capcom 2, Sonic Adventure 1 + 2, Chu Chu Rocket.

Weeeee're back! It's Craazy Taxi 2!

In all seriousness, the gameplay is amazing and one I pick up almost every day to try and beat my high scores. Although I did need a save-state to beat the Crazy Pyramid ;-;

That is a loaded question, I guess you never said homebrew to be excluded from this list if its not then the 90's shooters RadQuake Doom Doom 2 Half-Life, Also been playing the hell out of Jet Set Radio/Jet Grind Radio but that's not a homebrew port.

1. Shenmue
2. Omikron the nomad soul
3. Phantasy star

Power Stone 2 or Shenmue 2!

Jet Grind Radio
Project Justice
Resident Evil Code Veronica

Jpn
Radirgy
Karous
Capcom vs SNK 2

Sonic Adventure 1 and 2 but also very fond of Toy Commander.