M.U.L.E./YMMV


 * Adaptation Displacement: The theme song; it's been reused and adapted more than once, including appearing in the computer game Spore. It's likely lots of people have heard it and never known that the original game exists.
 * Broken Base: Planet MULE's auctions. A good half of the playerbase believes the "aucblocking" (raising the minimum buy line to a level nobody else can afford) is not an exploit and is how auctions were always supposed to be (keeping in mind that the original versions ran the timer down fast enough (and also had slower-moving avatars) to prevent 4-or-5-digit auction prices). The remaining half wants to force the aucblockers to pay for the land if they aucblock.
 * Ear Worm: The theme tune again.
 * Some Anvils Need to Be Dropped: Makes learning basic economic theory fun!