Blizzard continues to inch closer to finishing off StarCraft 2's long-awaited Heart of the Swarm expansion, with the latest update to the beta adding an XP-based progression system. The mechanic is specific to "Blizzard matchmaking modes and custom games on Blizzrd maps" and all XP is specific to the race you're playing as, earned "with each unit you build or destroy," according to a Battle.net post.
The levels cap out at 20 for each of the game's three races, the Terrans, the Protoss, and the Zerg. Since functional unlockables would ruin the carefully balanced RTS, player will instead earn cosmetic upgrades in the form of decals and portraits for their profiles. The new feature goes live in the beta with the next patch, though there's of course still no word on when Heart of the Swarm might be finished.