The site creates beats algorithmically and then they “evolve” to survive:
Our servers are regularly spawning new generations of a thousand unique patterns, each one being the cross product of two other patterns picked at random. The higher votes a certain pattern receives, the more likely it is to get picked and bear offspring into the next generation. This means that you may participate and influence the outcome of Patternarium simply by voting.
The beats are designed for uTonic and are public domain. You can download the “evolved” beats and use them with uTonic.