Okay, I've been kind of slacking on my posting lately. I've come across Gamification.org once in a while but have never take a good look around. However it looks quite disappointing from my scientific perspective so I think I'll rewrite a large part of it in the coming months.
Let's deal with achievements first:
Achievements are usually locked till a certain action unlocks it, a form of reward. Most often this is used in gamification in the form of a token. You can have multiple kinds of tokens used in the same game like coins, items and abilities. One defining feature of achievements is that they are a reward after fulfilling a fixed criterium. This is opposed to (partly) random token drops or random rewards in any other way.
They may be gained in every form of play like single player, cooperative play, competition or a combination.
However achievements can mean something different for each player for example; some simply want the token, some collect the tokens and some don't even care about the token.
Achievements can be implemented in a myriad of ways most of them are rewards after using a certain skill (task-contingent).
-It may be a reward of the improvement of skill compared to one's previous state.
-It may be a reward of improvement of skill compared to a fixed state.
-It may be a reward after displaying the skill in a certain way (efficiency, frequency etc.).
Other achievements can be linked to behaviour like attendance, performing a certain action (like the finishing the tutorial) and good sportsmanship. However compared to skill display, these behaviours are only displayed little. Behaviour specific achievements may therefore contain very rare achievements.
These achievements can be controlling a player's thoughts, this will decrease the skill of this player and happens mostly in case of harsh direct competition. Achievements can also be used as information by players to measure their skill level. Highly motivated players are theorised not to be under the influence of achievements and might not need them as an information source. This is related to their two main displayed motivation characteristics; desire to be good and the desire to become better.
Adiós, more next time!