Half-Life 1 _still_ runs fine on Windows 98 in my experience. But I got the game before it got Steamed (somehow I actually wound up with two physical copies... the first was the Adrenaline Pack which I bought new at Wal-Mart, but later the same pack but now including Blue Shift got released, and a friend who went full digital-only gave me his copy of those discs. So ummm.... I guess I have extra discs of HL1, TFC and OpFor which I don't need...)
Why the hell did Team Fortress Classic need a separate CD when its literally just an update patch (indeed its auto-installed if you skip the TFC disk and install the OpFor disk)?
On that note... one thing that bothers me about Half-Life is it seems some of its mods actually require Steam now. Back in the day you could go to ModDb and get stuff like They Hunger (which I thoughtfully backed up on a CD-R) and others which only required the latest at the time patch (which I also backed up on a CD-R--I was in the habit of backing up downloads in case the internet went down, and actually still am, I just use external HDs now). Nowadays though? I can't say for sure any mod will work on a non-steam version (they don't tend to say so upfront). I remember trying to play Afraid of Monsters and it decided to be an asshole. Like geez... Half-Life 1 runs in 98SE and XP, its mods should too.
I mean at least Doom WADs tell you when they need a specific source port.
....
So, wound up getting addicted to one of my favorite Windows 98SE games (well, originally a DOS game but there was a slight updated version for 95/98 PCs). You'll probably recognize it from these quotes:
"Skooboo. Zugzug. They're destroying our city!"
Orcs are so adorable.