You can access several options by clicking the gear icon in the upper left. Show names, skins and mass do as they say – show mass might be useful do know exactly how much bigger/smaller another player is than yourself. Furthermore you can change the theme to black & white or enable the Performance mode, which might to increase the games performance on low-resources devices. Another option regarding the games performance is limiting the FPS. Enabling mouse controls you can split by left clicking and ejecting mass by right clicking.