Demand-responsive transportation systems deal with the challenge of creating dynamic routes to accommodate user displacement demand. Given a user request, its spatial and temporal constraints influence the ease of allocating it and, in turn, the cost involved to complete it. Aiming to ease request allocation and reduce system costs, we propose a gamification-based algorithm that optimises the solutions computed for a demand-responsive transportation system. The gamification system aims to group user demand spatially and temporally through a reward system. Users who issue particularly costly requests are presented with a modification of its constraints together with a reward that incentivises the modification’s acceptance. In this paper, we formalise the problem, present the demand-grouping algorithm, and describe the user’s interaction with the gamification system. A case study is developed to exemplify the use of the proposal and its cost optimisation potential.