Powergaming is level advancement without character development (see next section for details). Sure, you can make an excuse like "My character is a fighter so he likes to go around killing stuff," but that does not make for an in-depth character and such a person will likely not be included very much in community affairs and relationships.
Powergaming is not against the rules, but it is not condoned, and chronic powergamers will be persecuted. A good rule of thumb is that if you reach level 20, the team should know who you are.
There is no real reason to powergame. If you want to be 40th level, fine. If you powergame your way to 40th level, and the team sees you do it, you probably won't be banned. But you also won't be part of any plotlines or special quests either. Basically you will shoot yourself in the foot because once you reach 40th there will be nothing for you to do in the world, and you will leave or keep powergaming characters to 40th until you get sick of it and then leave. Avlis will not miss you either, because you didn't contribute anything to it while you were here. It's the people who take time to smell the roses and put emphasis on roleplaying that will get the most out of Avlis, that being the old PnP feel of D&D.
Powergaming is the middle ground of the three things. Almost all forms of powergaming are frowned on, here on Avlis, but powergaming isn't normally enough in of itself to get you banned from Avlis. Extensive powergaming may do that, but you would have to do it a lot before it becomes an issue. However if you're busy powergaming, it's likely you'll miss out on opportunities to roleplay, which is the focus of Avlis.
Powergaming is generally defined as doing things for purely OOC reasons, mechanical advantages, or in game actions that are done to increase the power of your character, that makes no IC sense. It's related to metagaming because your approaching your character from the stand point of how to make her more powerful, rather then as a someone growing a character based on events that happen to her.
Like metagaming, powergaming isn't always bad, it's frowned on most of the time on Avlis, but there are a few cases where it could be overlooked, or even approved of. These however are rare cases, normally reserved for low level characters. (i.e. level 1-3)
Some examples of acceptable, and unacceptable powergaming actions. (Again these aren't hard and fast rules, just examples)
- Doing low level quests over and over again, to get your PC past the first few levels. Like a Fedex quest, or the firebeetle quest. (Doing a quest more then once isn't powergaming. But a mid to high level doing it like 10 times a night is.)
- Hanging out in one area to kill monsters or other NPC's over and over again, at low levels, to complete quests or gain some money.
- Going back into an area you cleared out, or respawning something you just killed, to get the final 50exps you need to level up, when you should have been in bed an hour ago.
- Taking a single level in a class, because of some benefit you get for having that class. (i.e. 1/19 Paladin/Sorcerer. Or taking a single level of Rogue, for the ability to pick higher then DC25 locks)
- Finding an area that allows you to make a lot of exp rather quickly, then spending several hours every day there, for no other reason then to gain a lot of exp quickly. (There's nothing wrong with monster hunting, or spending several hours doing it. It's only when you stay in the same area for hours that there's a problem.)
- Going to an area to kill NPC's or grab loot that would be against your characters beliefs in some way. (i.e. A paladin breaking into houses, or a dwarf looting a religious area sacred to dwarves)
- Rushing off the moment the server restarts to kill NPC's or open chests that you know drop good loot.
- Towing, taking lower level PC's with you in your party to reduce the average party level, for no other reason than to get more exp for yourself.
- Spending every moment you are on Avlis, killing monsters and gathering loot. (Again killing monsters and gathering loot, isn't bad. But if that's all you do, then there's a problem.)
- Having a really low score in one stat, so you can have a really high score in a different one. But not playing as if you had that really low score. (i.e. Having a 8 wisdom and charisma but acting as if you had a averge score in both.)