Players of the free-to-play MMO combat game War Thunder are reporting that purchasing achievement stage unlocks for the game's recently updated War Thunder Chronicles event may not work as advertised.

The game's development studio Gaijin Entertainment launched a special Holiday-themed update for the War Thunder Chronicles event last Friday that allows players to earn several new vehicles by completing several in-game achievements.

In the event players have to complete three achievements every two days for 10 different achievement stages, with every stage being available for those two days only.

On the game's website it lists that those players who have missed an achievement stage are able to purchase the achievement unlock via the in-game store, but players have now found that the in-game store achievement unlock is based on random chance.

The achievement stages can be unlocked by purchasing the Battle Trophy item from the in-game store that either rewards players with 999 Golden Eagles, a virtual currency, or the actual stage unlock.

As a result of the current implementation, players may find themselves receiving the virtual currency instead of the expected stage unlock. The game also prevented players from purchasing additional unlock items, effectively locking players out of the entire archievement.

On social media some players are calling the current scheme a "scam" because the random element of the Battle Trophy item is not made clear on the game's event information page.

In recent comments a War Thunder community manager stated that the game developer did not have a malicious intent when it designed the Holiday event, adding to it that the current issues are the result of a "miniscule" random element that had to be included to make use of the game's existing event system.

According to Gaijin Entertainment, players who are affected by the issues can contact the game's support team to have their achievement stages fixed.

The company did not comment on when it plans to release an game update to remove the random element included in the Battle Trophy store item.

Update: Gaijin Entertainment has confirmed that it is in the process of rolling out a game update to fix the issue.