Polygonal meshes (in particular, triangular meshes) are commonly used to represent and render models and objects in game applications. Due to speed and storage limitation, usually only coarse meshes and simplified meshes are used for rendering. To generate more details from a coarse mesh, several techniques can be applied, like normal mapping, displacement mapping, subdivision surfaces and other techniques. This thesis investigates efficient and adaptive mesh refinement schemes for rendering triangular meshes in modern games. Two schemes are proposed in this thesis: First, a subdivision scheme which applies Loop subdivision over multiple meshes is proposed to provide mesh surface refinement suitable for game applications. This scheme can overcome the difficulties of using subdivision in game applications. The implementation has been used in real commercial game engine. Second, a novel surface tessellation scheme based on PN (point normal) triangles is proposed. The new technique can perform fast adaptive tessellation and rendering using GPU shader processors, which achieves smoothness and speed in the same time. The scheme reduces the number of triangles used and it also reduces memory consumption and complexity compared to previous existing methods.