Random Events
The game is punctuated by a series of random events, forcing players to react to rapidly changing conditions as the game progresses.
Portals appear at random locations on the map (but not too close to any circle of power) and let in additional sappers to attack all players. Sappers emerge as quickly from a single portal as from all four circles of power combined, so they can force players' defenses to cope with a sudden and dramatic increase of attackers. The portals can be destroyed by heroes, who earn significant bonus experience for the kill.
Wormholes also appear randomly. Functioning like one-way way gates, worm holes give players and sappers alike new shortcuts to get across the map, often causing the sappers to suddenly attack from an unexpected direction when one appears. Like portals, wormholes can be destroyed by heroes.
There are sixteen gates on the map that can be opened and closed by heroes, but sometimes they also spring open or slam shut of their own accord, redirecting the flow of sappers and forcing players to reposition their defenses.
The trees on the map will sometimes spontaneously regrow, once again blocking off shortcuts that were previously cleared.
Occasionally sappers will cease their onslaught for a brief respite. When a moment of silence occurs, no new sappers will appear on the map for a period of 30 seconds. Sappers already present on the map, of course, proceed with their attack.