There is no actual Trader for these maps, instead a shop menu just appears between waves, regardless of where the player is.
There are also Medals you can earn for each map.
Unlike other games, you can also set the map to Random, which has the description of:
Can't decide where your horrific death...sorry, we mean "historic destiny"...awaits? Let us do it for you.
- Horzine Labs
- Hysteria Lane
- Industrial Madness
- Offices (Indoor Only)