hl1 had them combined.
Also hl2dm has suffered a lot due to not being associated with the singleplayer actually.
Up until the somewhat recent orange box update for all hl2 games, they hadn’t updated it in years despite all the bugs and lack of updated features it has, and it still has major bugs, a lot of which were introduced by switching to orange box engine.
HL2DM wasn’t even as updated as CSS.