This crops up from time to time in Survival of the Fittest — mostly because characters have a tendency to die before all the plans for them reach fruition. However a prime example would be the planned rivalry between Matthias Kovalenko and Eric Silvstedt, to the point where the pair even fought one another before the game to build it up. Once V2 began, though, the storyline got nary a mention and quickly fell by the wayside.
The "Original Character Battle Tournament" Infractus Fatality had multiple levels of They Wasted a Perfectly Good Plot. To start with, the tournament's creator designated one character the storyline hero, charging him with guarding a little girl from the nefarious machinations of one of the in-universe instigators of the tournament. The fact that an OCBT has no storyline hero until the final match has been judged was thrown into sharp relief when that participant lost in the very first round, at which point the child was handed off to another character. On top of that, because of the inclusion of the little girl, only people in the same bracket as the initial designated hero could be important to the storyline before the quarterfinals (the point at which the brackets would merge), basically rendering the others pointless. Then, just to waste the entire thing, the creator called the whole thing off after the quarterfinals for no better reason than that she lost interest. Despite this she still apparently plans to do a sequel tournament, which she has promised the semifinalists of the original a place in. That said, it should be noted that some participants have managed to give their parts in the plot at least a dignified sendoff by way of epilogues and such.
Your Favorite Martian's "We Like Them Girls" has a Lego setting, allowing for some good Lego-themed lyrics. What do we get? A generic rap song.
