It already didn't seem fair that existing players on the World of Tanks client cannot use Steam. Now they have offered exclusive "Free Summer DLC" to their Steam player base…
1x Garage slot
- A place for a new vehicle in your collection.
150,000 Credits
- Credits are the main in-game currency. You can spend Credits on new modules, equipment, and vehicles. Credits are also used to repair vehicles after battle, to purchase crew directives, and to resupply ammunition and consumables.
3 Days of World of Tanks Premium Account that provides:
- A +50% bonus to Combat Experience, Crew Experience, and Credits in every battle.
- An additional x3 multiplier to experience earned in a victorious Random Battle of your choice, that can be applied up to 5 times a day.
- An extra bonus of up to 750,000 Credits within 7 days. Also, a 10% bonus to Credits earned goes to a special vault.
- Three simple missions offering nice rewards.
- Being able to exclude up to two maps (instead of one).
- A 15% Credit bonus when playing in a Platoon. Also, Platoon members without the Premium Account receive a 10% bonus.
Source: https://www.reddit.com/r/WorldofTanks/comments/ov61wo/exclusive_on_steam_free_summer_dlc/