Having recently signed up for
The Backloggery gave me a new perspective on the concept of achievements. Since backloggery has their "B" and "C" statuses, I got the idea to list the achievements classes in alphabetical order from easiest to hardest. While that didn't exactly work out, I came up with these categories I think every achievement should fit into:
Accumulation: Each achievement for this category keeps a running tally of some number through all playthroughs of the game, such as score acquired, money acquired, or enemies killed, and the achievement is unlocked when the tally reaches a certain amount. These exist as incentive for the player to go out of their way to attain extra points or extra kills now and then, knowing that eventually they will hit that goal.
Beating: This category contains achievements that are unlocked through a standard playthrough of the game, and should all be unlocked if the game is beaten (warpless) and the player views the credits. For example, beating World X, or defeating Boss X would fall under this category.
Completion: This category contains achievements showing that the game has not only been beaten, but finished completely. Beating the optional bonus bosses, getting 100% items, beating minigames, and completing all difficulty levels would be examples of achievements in this category.
Domination: Achievements which are unlocked by playing through the whole game with minimal mistakes. No-death runs, no-damage runs, and no-miss runs would fall under here. There could be separate achievements for different categories of running, such as Any/100%, warped/warpless, and the like.
Exhibition: Situational bonus challenges for specific parts of the game. These would be special challenges such as "Killed all enemies in the pit on level 3 without touching the ground" or "Killed the level 4 boss with a hammer. These should be engineered to be interesting or tricky without being arbitrary.
Fun: Joke objectives, or rewards for failing. These are not serious achievements. A good example would be the infamous challenge in Punch-Out for Wii: "Knock down Glass Joe 3 times, then let him win by decision". These would include activating or beating the game with cheats, dying in certain ways, wearing specific combinations of clothing, and other arbitrary things.
Hardcore: Very special and high-ranked achievements for matching, or nearly matching, world records or speedrunners. These would require long-term dedication to obtain and would not be for everybody. They would probably be split up into multiple achievements for warped/warpless, and the like. Examples would be top-notch speedruns, very high scores, or obtaining Domination-class achievements in long games (we’re talking 8 hours or more) without saving.
Limitation: Beat the game with a self-imposed challenge, not using all of the game's features. Examples would be solo-character runs, no-weapon runs, runs that avoid certain powerups or rewards, pacifist runs, and so on. Unlike Domination-class achievements which could be ruined at any moment if you make a mistake, limitations are ongoing decisions by the player.
Maximization: Rewards for completing or maximizing values that don't specifically count towards 100% game completion. Examples would include maxing out every stat at 255, bombing every wall in the game, obtaining every type of powerup, or filling a logbook.
Repetition: Beat the game a certain number of times. Basically an accumulation award, but for beating the game.
Speedrunning: Beat the whole game, or individual parts of the game, in a time limit. The time limit would be a reasonable challenge without being hard enough to classify as Hardcore.
Technique: Pull off a trick. Unlike the Exhibition-class challenges, this would simply classify as "getting something to work". Examples from SMB would be Jumping the flagpole, getting 90 1-ups from a Koopa shell, catching a mushroom at the top of the screen, and so on. These tricks could be situation-specific, or be possible in multiple places.
Unless I'm missing something, all game achievements can fit into these categories. They could be designated by different colors on the webserver or as they pop up on the screen.