A limited body of research has investigated the influence of playing vernacular games (commercial games that are not designed for educational purposes), such as massively multiplayer online role-playing games (MMORPGs), on second/foreign language (L2) pragmatics acquisition. Furthermore, prior studies have revealed mixed findings regarding the utility of incidental L2 pragmatics learning through playing MMORPGs in fostering L2 learners' pragmatic competence. By using a pretest-immediate-posttest-delayed-posttest design and employing the interactionist approach, this study explored the effectiveness of playing an MMORPG (World of Warcraft [WoW]) in developing L2 learners' pragmatic competence in making suggestions and further investigated the affordances (target-language input, other players' feedback, L2 output) of playing WoW for L2 pragmatics learning. Intermediate English learners (N = 169) from a college in China played WoW with American players for four weeks. The results of written discourse completion tasks showed that the L2 learners preferred to adopt direct strategies (e.g. obligation statements like "You should …") for making suggestions in long-social-distance contexts on the pretest. In contrast, they tended to employ indirect strategies (e.g. modal verbs like "could") for providing suggestions in long-social-distance settings on the immediate posttest and the one-month delayed posttest. These findings suggest the advantages and lasting effectiveness of playing WoW in enhancing English learners' L2 pragmatic competence in making suggestions. Possible reasons, such as suggestion-related input and verbal implicit feedback (clarification requests) provided by the American players during gameplay, might have contributed to these L2 learners' improved suggestion-making performance in English.