So, you may have heard of this, Gas Powered Games is working on a new action-RPG type of game, mixed with MOBA and RTS elements. They also have a very amazing set of tools (Project Mercury) meant for mapping and modding, which will be released with the game, and will be used for future GPG games, RTS included. Suffice to say this set of modding and mapping tools is amazing and on-par with StarCraft II's. (Watch the 8 development videos to be amazed)
The project still needs funds and it has almost 2 weeks left for funding to reach the 1.1 mil $ goal on kickstarter.