Hmm. I don't know if they'd stand the test of time, but a few older games I enjoyed a lot back in the day that aren't going to show up much of anywhere due to age:
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Loony Labyrinth, a 2D video pinball game for the Mac and Windows by Little Wing Software. I've played huge numbers of tables on newer and more sophisticated engines, but that table kept me coming back for more hours of gameplay than any later ones. Not on GOG or Steam, though Little Wing sells copies directly.
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Flying Nightmares, or AV-8B Harrier Assault. Untextured polygon flight sim where you're operating off a US amphibious assault force; probably one of the few games kind of like Carrier Command 2 that I can think of in that you can also control other of your forces (though Flying Nightmares focuses on operating the Harriers, and Carrier Command 2 the amphibious assault ship). Doesn't look like GOG or Steam have them.
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Eufloria. Steam link for an HD re-release. One of those "real-time 4X" games, but using plants and seeds and minimalistic graphics.
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Hostile Waters: Antaeus Rising. A spiritual successor to Carrier Command. One has an amphibious assault ship, can construct autonomous vehicles and move your ship around. Unlike Carrier Command 2, this is a single-player game. Wish that someone would make a more single-player-oriented Carrier Command 2. The graphics haven't really kept up with the time, and it tends to encourage exploiting the AI's weaknesses, but I've had a lot of fun with it.
It's not exactly unknown within its niche, but because it is niche, Rule the Waves 3, a game that simulates naval fleet command and development.
EDIT: Oh, here's an oddball, not quite as old game: Ghost Master. One acquires and upgrades different types of ghosts, then places them and uses their abilities to scare humans away from a location. Nothing else very similar to it out there that I'm aware of.