The time has finally come for Phantasy Star Online 2 to be free of the Windows launcher and arrive on Steam. When that day arrives (August 5, by the way!), it'll bear some gifts for Steam users.
According to the official PSO2 blog, Sega is rolling out rewards for folks who log in on Steam. All you have to do is log into the game near the release date to grab the Headcrab Emote from Half-Life, as well as a number of booster items. If you finish any quest once on normal or casual difficulty (or higher), you'll get the Pyro's gask mask from Team Fortress 2, as well as the Alyx hairstyle from Half-Life Alyx.
For finishing any quest on hard/hardcore difficulty, you'll get a Wheatley evolution device, as well as a Left 4 Dead frying pan, a Team Fortress 2 minigun and a Half-Life crowbar. Continuing on (haha, this list is actually pretty great), for completing any quest on very hard difficulty or higher, you'll get a Half-Life HEV suit, and completing any quest for times on super hard difficulty will net you an Alyx replica outfit from Half-Life Alyx. Phew!
As a reminder, the game is cross-play and will offer cross-progress with the Steam edition. So you really have nothing to lose if you want to go for broke and grab these items: just know that in typical PSO2 fashion, they'll be "distributed at a later date." Good luck!
PSO2: Steam Launch Rewards [Sega]