Since require 'rubygems' and require 'rmagick' didn't work, I copied /var/lib/gems/1.9.1/gems/rmagick-2.13.1/lib/ contents and pasted them right in my project folder but then I've got this error message...

$ ./game.rb
/usr/lib/ruby/1.8/i486-linux/RMagick2.so: This installation of RMagick was configured with ImageMagick 6.5.5 but ImageMagick 6.5.7-8 is in use. (RuntimeError)
        from ./rmagick.rb:11
        from ./game.rb:14:in `require'
        from ./game.rb:14

Anyone knows how to fix this?