Our research work deals with the development of new learning environments. We believe that Game-based Learning can significantly enhance learning and that there is a real challenge in collaborative learning. That is why we have developed game-based learning multi-players environments. "Learning Adventure" (LA) is one of them and is equipped with the capacity for collaboration in certain activities. LA allows us to set up experiments with students in our university. We apply the metaphor of exploring a virtual world, where each student embarks on a quest in order to collect knowledge related to a learning activity. We think that the way of acquiring knowledge during a learning session is similar to following an adventure in a Role-Playing Game (RPG). The teacher describes the rules of the game (scenario) and can create a particular world according to the topic to be learnt. Each area of the world of LA is dedicated to a learning activity. Some collaborative tools exist in the LA world and can be activated in specific areas: a chat tool is of course available, but more specific tools such as a post-it notes wall or a collaborative feather can also be used. We describe these collaborative tools, and conclude through examples that they are good media for group activities, since they have been designed with the collaborative concepts in mind. However, in order to make the production of the group better, the group activity should be regulated. This regulation should occur when the group actions are not conforming to the group (social) rules. Special indicators linked to the collaboration of the participants are thus introduced in the learning environment (e.g. level of interaction or level of helpfulness). We illustrate our purpose with two case studies. The first one describes a collaborative problem solving activity in groups of fifteen post-graduated students and the regulation. Due to non-participation of several members of the group, the teacher had to monitor the collaborative activity in order to obtain a better group result. The second one deals with a sharing of results session where students were asked to use the collaborative feather to write a common document. Self-regulation of the group was observed.