This work discusses translation assessment practices, most importantly machine translation (MT) assessment. Relevant literature for MT assessment is discussed, from MT systems assessment to the design of error typologies for MT assessment. The study encompasses a series of three MT quality assessment experiments based on the language games as described by Wittgenstein in his work Philosophical Investigations. Game 1 encompassed post-editing two patent documents using different MT systems, and further evaluating translator s productivity and analyzing the edits made. The quantitative results showed the positive impact of using MT in productivity. The qualitative results included a typology of the edits made during the PE task in both MT systems, and the results achieved showed that increased productivity did not affect translation quality level. Game 2 compares two translations of the same text produced several years apart by the same translator. The former was produced using a CAT tool; the latter, a TA system. Both served as the basis for discussing the quality of translations produced in different systems and under different work conditions. Game 3 compares the post-edited documents produced in the PE task of Game 1 to the actual patent documents as filed in Brazil s Patent Office (INPI) in order to evaluate the impact of MT over the quality of post-edited documents. The results of both games 2 and 3 pointed to a superior quality of the post-edited translations of the present study over translations produced in professional contexts.