Multimedia capabilities of mobile phones increases all the time, today it is possible to develop games with advanced sounds and graphics. Games with 3D graphics are developing fast. But sounds are seldom used to enhance the experience. The sounds in mobile phone games are often one short midi music piece, under a minute long and only a few short samples are used. The sounds often become repetitive: it is common that people disable the music and sounds when playing on mobile phones. This Master of Science thesis in Media technology describes the development of a prototype and the experimental study that was conducted on it. The prototype is developed together with Interactive Institute, Sonic studio. The prototype is called The lair of Beowulf, Beowulf was a hero in a story which is the oldest written story in old-English. The game starts were Beowulf enters a cave, in the cave there are several unknown sounds to the gamer. The player of the game has no other cues of the game world than the sounds, which are played through a sound engine, called OpenAL. The game was then used in an experimental study. The study was conducted on 11 participants. This study had two parts: in the first part the participant was asked how they experienced the sound on seven given points. Experienced sound in this case was how they thought each location looked and the feeling they got from it. In the second part of the test questions about the whole game were asked. How easy it was to navigate, if it was fun to play and similar questions. The conclusion of the study was that it is very important to carefully select sounds. The illusion of the game world is more fragile when only sounds are used. It is more important to the context the sounds make the user experience in a sound mostly game, than in a game with where graphic describes the world.