A game that is free to play yet cuts the player off at key moments to demand payment. This can occur after losing too many lives, completing a chapter, or forcing the player to make a purchase in order to fulfill an objective necessary to complete a larger objective.
"Battle Nations is an addictive and hilarious turn-based strategy game that combines FarmVille with tanks! The game can be downloaded free, but players are free-to-pay for powerful, exclusive units and also to speed up construction time! Buy 1250 Nanopods for 49.99 USD, and get the edge on everyone else!"
by RedRockRun October 18, 2013