Various authoring tools have been used to ease the game creation. However, these pre-defined tools may not be suitable for some emerging or special domains. We proposed an approach named Game Creation with Customized Tools (GCCT) to create tools for certain domains first, and then create games using these tools. GCCT is based on the widely applied Model Driven Development (MDD) approach. Despite the apparent appropriateness and benefits, MDD also has drawbacks. Among them, non-trivial cost for tools development is prominent. To address this, some enhancements were made in GCCT, and two case studies were performed to evaluate the cost and the productivity when involving GCCT. In this paper, we reported the results of the case studies as well as practical lessons we have learnt.