At PAX East 2011, after the soon-to-be-famous (I promise, this thing will go somewhere) Bioshock Infinite phallic incident and enforcer dance party, we were able to do a brief video interview with Chris Rippy and find out some more about Robot's game.
The team expressed its interest in developing a brand new game for the company's debut in the industry; and hence, Orcs Must Die! was born as a unique tower defense / hoard hybrid. The enemies within Orcs Must Die! are standard goblinoids -- we've been told about the orcs, obviously, but there are also tank-like ogres, runners, fliers, and potentially more.
The trap system is largely operated from the player's ingenuity: instead of complex prefab traps to just slap into the floor (like those found in Dungeons), it's up to you to combine spring-boards with ceiling spikes or make use of map-specific props to obliterate the invaders. The game heavily focuses on a fast and fun core, while sprucing things up around the edges with replayability features, some of which reside within your head (such as trap combos and classic tower defense tactics).
Orcs Must Die! looks extremely promising and has a fast turn around, let's hope that Robot Entertainment proves itself as a company worthy of the prestige that Ensemble was once known for.
Look for the game in the early summer; we'll absolutely be reviewing it.