I was trying to think of which games created certain mechanics that became popular and copied by future games in the industry.
The most famous one that comes to my mind is Assassin’s Creed, with the tower climbing for map information.
I don’t remember being possible to spawn on teammates in BF1942, but definitely remember it as a first to select spawn points on map like Battlefield always did.
Battlefield 2142 had that, don’t know it that was the first one to do that though. Might’ve been BF2.
I remember an old BF1942 mod that had spawn selection; I don’t know exactly how far back the feature went, but it was around for a while before BF2.
I can’t remember if that mod had squad spawns. But I definitely remember playing it a lot, that was an absolutely revolutionary mod with so much content, not to distract from other great BF1942 mods though. I believe the original DICE team originated from that mod team to create Battlefield 2 as well.
There were a few BF42 mods that, on certain maps with certain vehicles, allowed you to spawn in vehicles.
IIRC, Forgotten Hope had a number of para-assault maps that allowed players to spawn inside of the aircraft they would parachute out of.
I believe you could also do this in… I can’t remember the name of it, but the Star Wars themed 42 mod (which the BattleFront series either largely copied or was directly inspired by), I think it had some spawn-in-able vehicles as well.
Also BF Vietnam, the official game, used a similar concept of having ‘tunnel exits’ that could be built/placed by Viet Cong engineers, which were placeable spawn points, and the US had the ‘Tango’ … mobile river boat with a helipad thing… which was a mobile spawn point.
I am 99% sure it was BF2 that first introduced being able to spawn on a player, I don’t think any of the mods for the earlier games pulled that off always had to be a vehicle or placeable static object.