Hacking a Minecraft game does have the potential to render the game unplayable according to the Minecraft Wiki community site. In addition, players using hacked games run the risk of being banned from specific Minecraft servers.
Hacked Minecraft games become unplayable in several ways, depending on the specific hack used. For example, hacks that increase a player's health to infinite sometimes result in data corruption when the player transitions from the game's netherworld to overworld or vice versa. Players using hacked Minecraft games are also often banned from Minecraft servers if the server's anti-cheating software detects the hacks used or if a server administrator suspects the use of hacked software by the player.