Electronic Arts mobile re-release of Dungeon Keeper has been found guilty of multiple breaches of the Committee of Advertising Practices rules governing misleading advertising, in a ruling that could impact other freemium mobile games.

The game attracted controversy soon after its release for discouraging negative reviews from players, but the new ruling by the Advertising Standards Authority centres on the two-tiered system of in-game currency. As with many mobile games, players earn one form of in-game money in relative abundance, but many elements of the game require a second kind of currency (in this case Gems) to unlock them. Gems are found extremely rarely in the game, but can be purchased directly from EA in quantities that range from around £3 up to £70.

While EA countered complaints about the games format by stating that it was possible for players to gain access to all the in-game content without spending any real money, the company itself refers to the two-currency system as grind and premium. In the original PC version of Dungeon Keeper, it took only a few minutes to clear a single patch of in-game land – in the new mobile version, it can take an entire day of gameplay.

The ASA ruled that claiming the game was free was disingenuous, as the protracted method of game progression meant that “players were likely to find themselves in a situation where they wished to bypass timers to achieve the expected gameplay as above, but were unable to do so without making a monetary purchase of the Gem currency.”

While the ASA stated that EA should mention the limitations of the free-to-play system in future ads, this form of monetisation is already prevalent among many game developers and continues to be lucrative. Dungeon Keeper has reached over 1m downloads on Android alone, so a significant shift in how two-tier currency games operate seems unlikely.