In the present paper, ToneInk, a prototype of a music-based play scenario that investigates player collaboration, is introduced. ToneInk is an explorative sound environment that differs from the majority of music-based games in that players can collaborate and be creative in the way they express themselves through melody and rhythm. The paper provides player interaction and navigation results and demonstrates how various affordances in the ToneInk design iterations make it hard or possible for players to engage with the system and with each other. From observations it was clear that players lost mutual awareness, and in general were more passive when they needed to monitor a screen interface that supported the sound environment. Player collaboration was strongest when players negotiated rhythm, while the negotiation of melody was temporally offset and consisted of long individual explorations.