It can be found cheaper at the Humble Store for £3.99
As far as I know, this is the cheapest this game has ever been.
Steam user score: Very Positive (11,296 reviews)
Spintires is an off-roading simulation video game developed by Pavel Zagrebelnyj and published by the UK publisher Oovee. In Spintires, players take control of off-road vehicles and drive them through muddy off-road terrain to complete objectives. Can be played solo, or join a friend in the game's coop mode.