To add the Oil Rush Tower Defense Map Pack:

For Windows/Linux:
1. Add "oilrush_dlc_td_map_pack.ung" to the "data" folder.

For Mac:
1. Right click (control click) the Oil Rush app and select "Show Package Contents"
2. Locate the "data" folder and add "oilrush_dlc_td_map_pack.ung" to it.