AirMech provides a very interesting blend of RTS and MOBA. The game is very feature-complete and offers a fair F2P model. Competitive modes and accesibility are excellent.

Brawlhalla is the best way to play a modern version of Super Smash Bros. on the PC platform. Excellent competitive features and player feedback. eSport tournaments and events integrated in-app.

Ashes of the Singularity is a fantastic iteration on the large-scale-grand-strategy subgenre of RTS. All the features desirable for competitive play are in place with the only exception of keybindigs.

Eternal offers a well-rounded CCG experience with a generous F2P model and competitive modes that are transparent and provide player feedback. Follow the link for an indepth competitive review.

Golem Gates offers a very interesting blend of CCG deckbuilding and RTS mechanics. Unfortunately, it lacks performance polish and competitive features such as ranked ladders. More details in the link.