Some elements of the 1E feel:
1. Amateurish rules system. I'm not criticizing - I'm just noting that the art of rpg design has improved dramatically in the past 30 years. In 1E days, if you needed rules for a specific situation, you made something up. Even if TSR published an official rule, it rarely used the same mechanic as another rule. The whole system was very ad-hoc, relying on GM's and players to keep the whole mess working. This tended to create a feel where anything was possible, but nothing made much sense.
You also had a LOT of rules arguments. I remember sometimes I would talk my group into taking a break from D&D to play wargames - because the wargames at least had fixed rules and we knew what could and couldn't be done in the game. Any given D&D session was much more a guess - you could never be sure what a GM would rule.
Rules systems today tend to be much more coherent, unified, and comprehensive. Sometimes even elegant. But they also tend to be more restrictive. Instead of arguing that something "can't be done" because it makes no sense, we argue that it "can't be done" because of the rules. As someone else posted, in 1E days the GM was "god", today the rules tend to fill this role.
2. Expendable characters and monsters. This is not true of all campaigns, but certainly in many. Sending a party of 6-8 characters into the dungeon and coming out with 2 wasn't uncommon. Death happened all the time. Monsters usually fought to the death and often lacked any motivation other than to fight adventurers.
3. Verisimilitude? What verisimilitude? One campaign I played in briefly had Cylons as guards for the baron. EGG wrote an article for The Strategic Review called
Sturmgeschutz and Sorcery, in which nazis fought trolls and evil high priests. The well-known Barrier Peaks module mixed Metamorphosis Alpha (a pre-cursor to Gamma World) with D&D. The First Fantasy Campaign, based on Blackmoor, had a dungeon guarded by elves with holy water hoses to keep undead from following adventurers as they left the dungeon.
4. Diablo-style play. Kick in the door, kill things, take their stuff, rinse and repeat. This was standard. Roleplaying was in its infancy and it took time for most groups to change styles. And the high death rate of characters (see point 2 above) tended to discourage roleplaying also.
5. GM vs Players. GM's were "god" and only bad players disagreed with the GM, even when so many GM's were clearly lousy. The rules often encouraged GM's to "get" the characters, using cursed items, stealing their stuff, setting up killer traps (save or die), and so on. EGG had a big influence here - one has only to read some of his Dragon articles or read through Tomb of Horrors to see this style in all its glory.
6. Power. C'mon, admit it? How many people here never played, even once, in a game where the party had artifacts, took on gods, killed Tiamat, etc.? Monty Haul became infamous for a reason.
7. Wonder. Everything was new, strange, exotic. The lack of comprehensive rules, e.g., item creation, led GM's to come up with some pretty amazing, orginal stuff. Also some pretty unbalanced, unfair, absurd stuff. But that was part of the fun.
It might be more diplomatic to say that I think they are both very good systems, I just happen to like 1e better.
