I've trimmed this down.. so here we go...
- save points or checkpoint saves. I _strongly_ prefer being able to save whenever I feel like it, esp in RPG games.
- Underwater level are normally fine (super mario bros 3 were ok) underwater levels that also require air are annoying. actually it can be highly stressful vs entertaining.
- % bosses. percentage bosses have a small percentage chance to automatically win via a rare serious of attacks that are completely unavoidable and cause you to lose the fight, with zero chance of suviving, period, regardless of gear items ability etc. MMOs are terrible at this grr, remember 4 horsemen pre wow expansions :S
- something I call MSG4 boss syndrome. Basically I _hate_ bosses that make you hunt them, you get 2 hits in doing 0.1% damage out of their life bar then you have to spend the next minute or so trying to find them or dodging them from a-far. While this makes a boss take 14 minutes todo, I'd fight a boss for 14 minutes that I can hit whenever I feel like vs peek-a-boo tactics.
- Games with no bosses. even if the bosses are reasonably easy, I like them, add them, just so long as it isn't MSG4 styles grr. People feel better after defeating the big bad.
- Little Bosses. By design I like my bosses to be big, because big is epic. Check Most of God of war 2's bosses for details.
- id software Game syndrome. A term I made up after Quake 2, basically id software games are simple games (by choice) that focus pretty much solely on graphics with virtually no gameplay or progression of gameplay at all. Games with little gameplay and entertainment are trash games, pretty games with little gameplay and entertainment are still trash, just pretty.
- EA Sequel Syndrome. Change of names here, 2 or 3 new textures here, update name roster RELEASE! 100% hate, as normally gameplay doesn't change what so ever and flawed game design doesn't get fixed.
- Difficulty levels. Sadly alot of games today are designed to be a little too easy on normal skill level (normal is the new easy skill level it seems :/). I think its because designers have forgotten how to make a game difficult without resulting to unfun mechanics such as cheap bosses and % chance to automatically lose no matter What.
- Forced Replay of levels. I HATE games that force me to replay everything before hand. in RPGs I can handle a little backtracking but in 3d platformer games, completing everything then getting forced to basically replay everything again to clock the game is just poor.
- Dodgy 3rd Person Camera Syndrome. I've seen some potentially good games simply destroyed by this. While normally a programming problem, map designers quickly learn if their camera system or camera control system isn't up to scratch with the maps they are designing and should adjust their map design to help limit the frustration. In the end if you can't get it right, God of war 2's fixed camera (camera on spline rail) will serve you well.
EDIT: ok decided to add one more
- Dodgy Pathfinding.. right, firstly Learn A* pathfinding algo (ok bit memory expensive on the DS but yeah), next ensure that everything can navigate their way around something and can't set stuck in the environment. if the dodginess is caused by insane unit count, compromise, let some units travel through each other so the player doesn't get driven insane with units deciding to go virtually to the other side of the map to get 2 meters in front of them.