Children with autism spectrum disorders (ASD) often exhibit impairments in communication and social interaction, and thus face various social challenges in collaborative activities. Given the cost of ASD intervention and lack of access to trained clinicians, technology-assisted ASD intervention has gained momentum in recent years. In this paper, we present a novel collaborative virtual environment (CVE) based social interaction platform for ASD intervention. The development of CVE technology for ASD intervention may lead to the creation of a novel low-cost intervention environment that will foster collaboration with peers and provide flexibility in communication. The presented Communication-Enhancement CVE system, Hand-in-Hand, allows two children to play a series of interactive games in a virtual reality environment by using simple hand gestures to collaboratively move virtual objects that are tracked in real-time via cameras. Further, these games are designed to promote natural communication and cooperation between the users via the presented Communication-Enhancement mode that allows users to share information and discuss game strategies using gaze and voice based communication. The results of a feasibility study with 12 children with ASD and 12 typically developing peers show that this system was well accepted by both the children with and without ASD, improved their cooperation in game play, and demonstrated the potential for fostering their communication and collaboration skills.