"Once the launcher has been installed and your key redeemed, just select Riders of Icarus and click PLAY! Remember, you only have from Thursday, April 21st until Thursday, April 28th to participate in the Phase 2 Closed Beta test. As you play, make sure to give us your feedback on our forums and be sure to look out for our survey. And don’t forget that all Riders who participate in our Closed Beta tests can expect a special reward that can be redeemed during Open Beta."
Taken.
It's access to Closed Beta game.
"Once the launcher has been installed and your key redeemed, just select Riders of Icarus and click PLAY! Remember, you only have from Thursday, April 21st until Thursday, April 28th to participate in the Phase 2 Closed Beta test. As you play, make sure to give us your feedback on our forums and be sure to look out for our survey. And don’t forget that all Riders who participate in our Closed Beta tests can expect a special reward that can be redeemed during Open Beta."
Official game website here.
BTW my other topic here.