Unfair difficulty: Arcade ports most, but there are quite a few games that were designed around being quarter munchers, but instead made it to the NES or something else.
Passwords bigger than 10 or so characters: I have a few games that have really bad password systems. I think one has a 32 letter and the other has a 64 letter password. And if you mess up a single letter, it's wiped so you have to type it out again.
CD-Keys: Digital distribution is a great thing for pc games. I remember having to type in Sooooooooooooooo many CD keys when I would get a new computer.
Unskippable Cutscenes: I loved the combat in games like Golden Sun, but I can't be asked to replay them, mainly because some fights have like 5 to 10 minutes of unskippable crap beforehand.
Horrid or Obtuse UI's: There are a few games that I couldn't play back in the day because I didn't understand the UI and lacked a manual. I couldn't play X-COM back in the 90's because I didn't understand the UI or anything, but after I watched an LP, I understood enough to play.
Bad/Unmappable Controls: Enough said, When you're used to B being to jump, and some game uses X, and you can't change it, it makes you accidentally attack when you mean to jump or something. Not a big deal nowadays with tutorials, but can still be annoying.
"Please Insert Disc 2": I forget what game I had that did this, but the game was split among 4 discs, but unlike a smart game where the world map content would be on all 4 discs, it was evened out on all 4, and if you had to backtrack (which was required a LOT between discs 1 and 2) you had to swap discs EVERY time you went between the sections of the world.
No Waypoints: Maybe I'm a spoiled casual scum, but I recently bought Morrowind and I cannot stand it. Yes, I know the game gives you directions in your quest log, but I really wish I could have a marker on my map or something. Maybe not an arrow pointing me everywhere but just a marker where you need to go on your map.
Probably a ton of other things, but I think I hit the big ones.
Passwords bigger than 10 or so characters: I have a few games that have really bad password systems. I think one has a 32 letter and the other has a 64 letter password. And if you mess up a single letter, it's wiped so you have to type it out again.
CD-Keys: Digital distribution is a great thing for pc games. I remember having to type in Sooooooooooooooo many CD keys when I would get a new computer.
Unskippable Cutscenes: I loved the combat in games like Golden Sun, but I can't be asked to replay them, mainly because some fights have like 5 to 10 minutes of unskippable crap beforehand.
Horrid or Obtuse UI's: There are a few games that I couldn't play back in the day because I didn't understand the UI and lacked a manual. I couldn't play X-COM back in the 90's because I didn't understand the UI or anything, but after I watched an LP, I understood enough to play.
Bad/Unmappable Controls: Enough said, When you're used to B being to jump, and some game uses X, and you can't change it, it makes you accidentally attack when you mean to jump or something. Not a big deal nowadays with tutorials, but can still be annoying.
"Please Insert Disc 2": I forget what game I had that did this, but the game was split among 4 discs, but unlike a smart game where the world map content would be on all 4 discs, it was evened out on all 4, and if you had to backtrack (which was required a LOT between discs 1 and 2) you had to swap discs EVERY time you went between the sections of the world.
No Waypoints: Maybe I'm a spoiled casual scum, but I recently bought Morrowind and I cannot stand it. Yes, I know the game gives you directions in your quest log, but I really wish I could have a marker on my map or something. Maybe not an arrow pointing me everywhere but just a marker where you need to go on your map.
Probably a ton of other things, but I think I hit the big ones.