Immersive VR, a technology getting attention in recent years, is widely applied to the realm of serious games because it can provide users with both fun and intriguing experiences. This poster proposes a self-training VR serious game for fire evacuation drill with concurrent tele-collaboration among avatars controlled by and synchronized with multiple-users in remote places. We introduce a system architecture of both single user and its extension to multiple-user system. The single user system consists of wearable sensors and 3D VR HMD to synchronize a user's motions to one's own avatar in the virtual environment. We can easily extend the system to the multi-user mode through the Unity game cloud server. The multi-user mode enable players to experience a tele-existence so that they can collaborate in the virtual environment, and they can concurrently navigate while interacting with virtual objects as if they coexist in the same space.