Based on Negroponte's idea of man-machine symbiosis, this thesis proposes: Co-Build - A real time web based collaborative 3D modelling platform. The aim of the study is to understand the symbiosis by extracting different circumstances under which contributions from co-creative agent (machine) appear to make sense. And by extracting different aspect of human - human collaboration that can be applied to human - machine collaboration. The machine behavior is based on enactive model of co-creativity. For the purpose of the study, machine intelligence is emulated using the wizard of oz technique and the machine action is restricted to mimicking. To simplify the complexity involved in architectural design process, the study focuses on additive massing models, specifically in the context of concept design game which focuses on interaction namely, the silent game. Further two variations of silent game namely, switch silent game and simultaneous silent game are proposed to test two kinds of interactions between the collaborators namely, turn-taking and simultaneous interactions. Further, the study reports the results of an online user study with 20 participants. The user study involves participants playing both the variation of silent games first with a human and then with the wizard of oz machine. Retrospective video walkthrough and post task interview are the methods utilized to collect data for evaluation.