The last game before Artifact other than some F2P stuff that they farmed out to places like Nexon (and The Lab, which was a pack-in tech demo) was Dota 2, which

The last game before Artifact other than some F2P stuff that they farmed out to places like Nexon (and The Lab, which was a pack-in tech demo) was Dota 2, which hit beta in 2011. Seven years is a large gap for a game company.