  Quantum Moves is a citizen science game that investigates the ability of
humans to solve complex physics challenges that are intractable for computers.
During the launch of Quantum Moves in April 2016 the game's leaderboard
function broke down resulting in a "no leaderboard" game experience for some
players for a couple of days (though their scores were still displayed). The
subsequent quick fix of an all-time Top 5 leaderboard, and the following
long-term implementation of a personalized relative-position (infinite)
leaderboard provided us with a unique opportunity to compare and investigate
the effect of different leaderboard implementations on player performance in a
points-driven citizen science game.
  All three conditions were live sequentially during the game's initial influx
of more than 150.000 players that stemmed from global press attention on
Quantum Moves due the publication of a Nature paper about the use of Quantum
Moves in solving a specific quantum physics problem. Thus, it has been possible
to compare the three conditions and their influence on the performance (defined
as a player's quality of game play related to a high-score) of over 4500 new
players. These 4500 odd players in our three leaderboard-conditions have a
similar demographic background based upon the time-window over which the
implementations occurred and controlled against Player ID tags. Our results
placed Condition 1 experience over condition 3 and in some cases even over
condition 2 which goes against the general assumption that leaderboards enhance
gameplay and its subsequent overuse as a an oft-relied upon element that
designers slap onto a game to enhance said appeal. Our study thus questions the
use of leaderboards as general performance enhancers in gamification contexts
and brings some empirical rigor to an often under-reported but overused
phenomenon.
