We analyze from the game theory point of view Consensus-based blockchains when participants exhibit rational or Byzantine be- havior. Our work is the first to model the Byzantine-consensus based blockchains as a committee coordination game. Our first contribution is to offer a game-theoretical methodology to an- alyze equilibrium interactions between Byzantine and rational committee members in Consensus-based blockchains. Byzantine participants seek to inflict maximum damage to the system, while rational participants best-respond to maximize their expected net gains. Our second contribution is to derive conditions under which consensus properties are satisfied or not in equilibrium. When the number of votes required for a decision is lower than the proportion of Byzantine participants, invalid blocks are ac- cepted in equilibrium. When the number of votes needed is large, equilibrium can involve coordination failures, in which no block is ever accepted. However, when the cost of accepting invalid blocks is large, there exists an equilibrium in which blocks are accepted if and only if they are valid.