We had our very first PC in 1987 - a 8088 XT clone 8mhz CGA, upgraded to EGA a couple of years later.
I remember most new games coming out in 1990 were too demanding for the venerable XT - most of them started to support VGA, FM sound, and some started supporting expanded memory as well (Wing Commander 1 comes to mind), thus making owning an AT machine mandatory to play. Eventually my parents replaced our XT by a 386SX16 with VGA sometime around 1990.
That being said, i have very fond memories of our XT clone, with its shoddy keyboard (the space bar would keep falling apart because of being repeatedly bashed); its very loud speaker that you couldn't turn off, and its less than accurate joysticks.
Here are some of the games I remember playing on it:
CGA Booter Games or Early DOS:
Arkanoid
Boulder Dash
Burger Time
Tapper
Dig Dug
J-Bird
Styx
Moon Patrol
Striker
Zaxxon
Decathlon
California Games
World Games
Winter Games
Summer Games
Sierra Boxing
Macadam Bumper
Dark Side
Gato
Pitstop II
4x4 Off Road
Crazy cars
Le Manoir de Mortevielle
Defender of the Crown
The 3 Stooges
EGA Games:
Rick Dangerous
Techno Cop
Targhan
Grand Prix Circuit
The Cycles
Test Drive
Test Drive II: The Duel
DeathTrack
GhostBusters II
Zak McKraken
Indiana Jones and the Last Crusade: The Graphic Adventure
Maniac Mansion
Monkey Island
I think it's really cool that you are building an XT and would love to do it too at some stage, but I find the project a bit daunting as it doesn't seem as straightforward as slapping a few parts together and coming up with a Socket 7 machine that just works. Also, I think an XT is not really complete until you pair it with a CGA or EGA 9pin monitor and these seem to be impossible to come by these days 🙁