As pig farmers in Happy Pigs, players compete on raising healthy pigs by executing strategic combinations of Actions (Feed, Mate, Purchase, and Sell) and Tools (Vaccines, Nutritional Supplements and Birth Amulets) for each round. Both the frequency to take these Actions and the number of Tools a player can purchase are restricted by the number of players choosing to take the same action in any given round. Also, from time to time there are unexpected events (such as Pig Shows and Sausage Fest) which offer players great opportunities to outperform their peers.

There are four rounds to each season, and all unvaccinated pigs die at each season change. The game concludes at the end of four seasons, when all pigs are sold off at different prices in accordance with their sizes. The player with the highest profit at the end wins the game.