What and Why?
A games convention is a three or four day games-fest held to run and play various types of roleplaying games. It's not just for established gamers - plenty of games are written and presented specifically for newcomers to roleplaying. If you're new to gaming, keep an eye out for the games with little or no system knowledge - these games are easy for new roleplayers to pick up quickly and run with.
If you're an established gamer, you can try out game systems or playing styles that are new to you, especially freeforms (which are rarely run outside of conventions), see how others write and run a game, and pick up some new approaches to old games. You can meet other gamers who share your interests and swap anecdotes and ideas. You also have a chance to buy gaming stuff you probably haven't seen before. If you're into minatures or board games, it can be hard to find opponents (and time!) - a convention provides a meeting place for plenty of fellow enthusiasts.
People who come to games conventions are generally eager to have a good time, forget about mundane matters for a few days, mingle with other players and generally play games until they drop.
Most of all, conventions are fun!
So what's Arcanacon about? All of the above, really. More specifically, Arcanacon provides an opportunity for gamers to share the many facets of our hobby. We want to promote roleplaying to both existing gamers and interested newcomers, and to provide a forum for new ideas and innovations. Most importantly, we all want to have a good time doing all of this!