The best example of gameplay loops I can think of. A very relaxing game when played in isolation, the loop of exploration > rewards > level > clear enemy camps > items > conquer > explore is genius in simplicity and multifaceted in execution, and all the factions offer at least one good reason to play them. Add in some depth in regards to what heroes, upgrades, build orders, etc. are necessary for matchups and maps and you get a very simple to understand yet intricately mechanical strategy game, which is the best you can ask for. HOTA is a much welcome expansion, seamlessly integrating with the base game, at this point it's pretty much a stark upgrade over the base game, though balance is still inherently wonky.