With over twelve million game plays, the original GemCraft became a massive success. The difference between GemCraft 2 and other tower defense games is the ability to mix and match your own gems. The gems are your work force and will stop the evil monsters from penetrating your own fortress. When killing monsters you gain mana which is needed to create new gems and upgrade old ones, which is highly needed when the over monsters become many and overpowered.
When you've managed to take down all the monsters on the field you have become victorious, and you will see your total score. The total score will become a motivation throughout the game as you level up once you've gotten a certain amount of points. When you level up you will be able to choose new skills from the skills list, and when you've done something extraordinary in GemCraft 2 you will receive amulets that proves your heroicness. As well as gaining skill points and amulets you will also unlock new levels as you play along. New levels means more waves of monsters, and which again equals to more cash, skill points and amulets.
Quick tip: Having few and overpowered gems in GemCraft 2 might be more useful and handy rather than having many weak ones that will costs half the price and do half the work.