Sanctum is a fun and challenging game. It requires you to balance resources and defense structures. The goal of each map is to defend a core from incoming waves of monsters. Simple right? It's not. Each wave is unique in that the content varies. Some waves may only contain one monster, while another wave can contain many types. Each monster has a specific weak spot that you target to kill them more effectively. You have to destoy these waves by constructing an efficient maze of towers and guns. But you don't have unlimited resources; only what is given to you after each wave. That's when creativity and balancing come into play.
The game is even more fun under mulitplayer mode. With more people, you have more resources to spend to defend your core. However, the monster waves are random and stronger than the single player version. Communication is key to having a sucessful game. A method that can be used have each person focus on a type of tower (one person can focus on anti-air and floors, while another one could focus on ground and laser towers)
This game was worth the purchase. It provides you with a great challenge. Be warned though because each round can take up to an hour or more. If you have plenty of time to kill and want a challenge, then this game is for you. But if you don't have the time or patience to play, skip this game. There will be times where after playing for 45 minutest to an hour, you find out that your core has been attacked and you no longer have that 100%. You quit and then you resume from last save. So have paitence when playing this game.
One last note: Play around with the multiplayer chat. You'll be laughing a lot.