In this work we study on a 2-dimensional square lattice a recent version of the Naming Game, an agent-based model used for describing the emergence of linguistic structures. The system is open-ended and agents can invent new words all along the evolution of the game, picking them up from a pool characterised by a Gaussian distribution with standard deviation $σ$. The model displays a nonequilibrium phase transition at a critical point $σ_{c}\approx 25.6$, which separates an absorbing consensus state from an active fragmented state where agents continuously exchange different words. The finite-size scaling analysis of our simulations strongly suggests that the phase transition is discontinuous.