There's no fixed route, every tower you drop becomes a wall, so you literally build the maze that funnels enemies through your crossfire.
Enemies enter an open field and head for the exit, always taking the shortest route available. Because your towers block tiles, each placement reshapes their path, arrange towers to herd the horde down a long, winding gauntlet past as many of your guns as possible. Just don't fully wall off the exit. Hold the line through every wave.
Maze Keep draws on open-field tower defence, which browser games established in the mid-2000s — Desktop Tower Defense in 2007 was the breakout, and it is the version that fixed the form in most people's minds.
There is no fixed path. Attackers walk toward the exit by the shortest route available, so the towers you place ARE the maze, and building is the same act as routing. That produces the signature tactic and the signature disaster: a long corridor multiplies your firing time, and sealing the route completely is usually forbidden, so a misplaced tower can suddenly open a straight line to the exit you spent the whole level preventing.
Maze Keep is an original free browser game in the open-field (mazing) tower defense tradition, where your placements define the enemy route. Just open and play.