Slot Machine: Philip Linden
Fully Functioning Blackjack: Tcoz Bach
FPS and Mission Based FPS Games: Tcoz Bach (Nexus7 Arena, now The Vorago)
RTS Game: Tcoz Bach
Real NPC: Tcoz Bach (InfoBot in NexusPrime)
Pooltable: Tcoz Bach
Plinko: Dave Zeeman (before 02/26/03)
Snowball Game: Nick Fairlight
Fully Playable RPG: DarkLife
Chess, Majong: Xylor Baysklef & Co.
3-D Tank Combat: Project TEA - SL Game development competition - Hiro Pendragon, Milo Bukowski, Adam Zaius (Collateral Damage- Vehicle based combat was made in 2003 by Lance LeFay, but it was sucky, so it doesn't really count.)
First Successfull Gambling: When DarkWood opened in Winter 2003, wishing well! SL gambling was born!
RPG Game: Coded by Mark Busch for DarkLife
Game Made Purely In SL To Be Licensed In RL: Tringo by Kermitt Quirk
Skill Sploder After Gambling Ban Roberto Salubrius
Combat game using combo keys for making special attacks: Kyrah Abattoir (as far as i know) in Transylvania
Parachute / Skydiving Equipment: Al Bravo
Scripted Soccer Field: Roberto Salubrius