OK, I took the Wikipedia list of ColecoVision games, and trimmed everything that wasn't an arcade port. I count "only" 44 of them, which is still a fair piece of the original library and says a lot about the time period. Choplifter and Pitfall II were arcade games, but since they were ports FROM a home version, they don't count. I'm sure someone will sing out if I made a mistake.
I think it's pretty easy to cull 19 games you don't want and still have a very nice collection.
Here's the full list:
Buck Rogers: Planet of Zoom
Bump 'n' Jump
Donkey Kong Jr.
Mr. Do!'s Castle
Roc 'N Rope
Star Trek: Strategic Operations Simulator
Star Wars: The Arcade Game
I would lose:
Carnival (boring), Centipede (because it's on literally ever system ever), Congo Bongo (looked good in olden times, plays poorly), Front Line (never liked this or most military-themed things), Galaxian (because it's old and tired), Omega Race (just don't like it much), Roc n Rope (admittedly because I never played it), Slither (needs roller controller to play well), Space Panic (yawn), Spy Hunter (much better ports elsewhere), SubRoc (meh), Turbo (amazeballs once upon a time, but no more), Tutankham (did anyone ever like this?), Up n Down (meh), and Victory (even though it has a Rebel Armored Snowspeeder
on the marquee).
That's fifteen gone. I need another 4 to get down to "only" 25, and I am starting to appreciate that this is harder than it seemed. Oh, if only there were a "Donkey Kong Classics" with both DK games. This last bunch hurts a bit.
Looping (it's a unique port, but it's not as fun as it once was), Star Wars (because it doesn't really do justice to the arcade game), Super Cobra (because we have Cosmic Avenger, which I think is very ColecoVision)
Still need one more. In my heart I know that I don't need Lady Bug AND Mouse Trap, but they both seem so iconic. Just pick one for me, please.