Awesome game, but the game gets really repetitive after level 30. After that, it's just jamming for xp. Don't get me wrong, the game is genius, but it needs something to entice me to want to play this game again.
Adding on to what BavarianDude said, by using the Orange-Red (RO) supertrap strategy, you can have millions of max mana without cheating and score trillions of points.
One of the best things about this game is that there are so many levels of play - when you think you've figured out the best possible method of playing the game, something you had previously ignored pops up and you realize that there are even more effective ways to score trillions of points.
A challenge for anyone who has scored >10 Billion points on a single level before - beat all 228 waves of the last level. Read up on the Gemcraft Forums. (also, help us with unlocking to beat all 512 waves).
@trishika - no: supergemming is better. RO supergem brings in more mana than you can spend. Read the forums for more information. Seriously, you can score trillions. Read the forums.
@lc3ki11a - Summoning a monster occurs when you drop a gem bomb on the sidebar. It increases the score. It is very useful to increase your score drastically. This is how the high scorers get billions of points.
@xelux - Psycho class is not for "experts" - you just need to learn the 4 different builds which allow you to get past opponents much faster than the 1 build for bio. Read the In-Depth Sonny 2 Psychological Legend Guide with Zones 6 and 7 - it is available on the Kongregate forums, and will provide tips for all the fights and in-depth analysis for fights which are difficult. I achieved Legend using a psycho while only dying once (against the City Council, cause I didn't re-spec).
I am the 12th highest all-time highest score (on Kongregate) reached in one level without speedhack / macros / cheating / etc! Many of the scores on the high score list are insane, but legitimate.
The easiest way to get past the first epic boss is to spam Mana Pool on the earlier levels - it gives you a 8% point bonus and max out Lower Mana Cost for Gem Creating and Combining - level up to at least 23, and spend some points on ... Don't forget to use the gems from your towers to gem bomb the Boss. I always had trouble against this guy, but he was very easy using this strategy.