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Curve Suggestion: A curve with really bad stats (even worse than basic snake). However, you get double (or more) coins/gems from your games with it.
Well that depends what you mean by worse but I like the idea :D Super slow, fat and huge turn radius? Would be utterly impossible to win with. Or maybe really really fast but huge turning radius and fat.
Or maybe unlocking secretive achievements - for funny tasks like winning in Arena 3 with Snake or Ant.