Lost Souls MUD/YMMV

• Broken Base: The late 1990s saw a drama-filled political schism among developers and players alike, leading to a splinter MUD called Lost Dawning (originally a "tutorial MUD" for Lost Souls) that was dedicated to what Lost Souls had been before it was Ruined FOREVER by a developer called Chaos. (Chaos now runs Lost Souls completely, and Lost Dawning is dead.) Another base-breaking came circa 2004 when massive code revisions remade the game so as to be nearly unrecognizable to older players.
• Demonic Spiders: Probably best exemplified by scrub NPCs with "amulets of retribution", items that hit you back (once) if you hit their wearer with an attack of a specific type. Also literally, as with the rhax species, and depending on how broadly you want to apply "demonic", the spider lloigor Nachthla.
• Epileptic Trees: The complexity of the systemry regularly leads players to come down with fits of contagious apophenia. A historically popular topic for this has been the effects of different colors of flux weapons.
• Goddamned Bats: Rats and bats can be a bit of a pain for newbies because of their dodginess.
• Serial Numbers Filed Off: A trend for the past few years has been to rename things that were originally based on other people's intellectual property in some way.
• That One Boss: The spider lloigor Nachthla, a being of primal power whose idea of fun is making physical forms for itself that embody the principle of predation.