Orcs Must Die

- Use barricades to create chokepoints, and then heavily trap those chokepoints. Wallblades are awesome early on: If you can make the enemies walk past three or four wallblades with tar traps on the floor, you'll already get rid of most enemies except for goblins and boss enemies. Put brimstone before, in and after the main chokepoint to mop up those goblins. As soon as you get the clockword mace, use it whenever you can. Grinders are pretty good too.

- The biggest threats to your barricades are ogres and sappers. With the former, take care not to come within striking distance while they're next to a barricade, or they'll hit it when they attack you. Sappers are tough to deal with, since they will often beeline for your barricades. Try to remember the waves in which they show up, and during those waves, stand in front of your barricades. This will usually cause the sappers to charge you instead of those expensive barricades.

- Archers and paladins are awesome. Put some archers with the fire arrow upgrade near your chokepoint, and watch your combo multipliers shoot up. On levels where it's difficult to create good chokepoints, a small army of paladins backed up by archers can save the day.

- Steel Weaver is the best weaver for most maps, either because of the trap upgrades, or the guardian upgrades, or both.

- The storm cloud is awesome, especially when used near your chokepoint.