In this work, we introduce and experimentally evaluate a new hybrid software-hardware Transactional Memory prototype based on Intel's Haswell TSX architecture. Our prototype extends the applicability of the existing hardware support for TM by interposing a hybrid fall-back layer before the sequential, big-lock fall-back path, used by standard TSX-supported solutions in order to guarantee progress. In our experimental evaluation we use SynQuake, a realistic game benchmark modeled after Quake. Our results show that our hybrid transactional system,which we call HythTM, is able to reduce the number of transactions that go to the sequential software layer, hence avoiding hardware transaction aborts and loss of parallelism. HythTM optimizes application throughput and scalability up to 5.05x, when compared to the hardware TM with sequential fall-back path.