Literally Insane Racing

Literally Insane Racing was made over the course of 2 months for Mousebreaker. It is a racing game, and very large - 40 cars, 60 races, car customisation, and a campaign that takes 2+ hours to complete. It is the spiritual successor to Slide Racing, and implements the Box2D physics engine.
The cars are very carefully balanced, so that every single car has an event where it will do well. This is achieved through races having entries limited to cars from certain countries, or with different drivetrains and so on. The player is expected to use 15-20 of the cars in their playthrough, meaning that they will end up with a garage personal to them and giving a sense of ownership. Two different players can make genuinely different decisions in their car purchases and what they choose to upgrade, and still progress through the campaign.
According to my analytics, and despite there being no incentive, a percentage of players continued grinding after completing the game to collect every last car. I believe that this demonstrates the power of giving players something to own, in a somewhat Pokemon-esque manner.