Remote rehabilitation systems allow the supervision and monitoring of physical exercises by therapists without the need to move, temporally and spatially, the patients who perform them. The main advantage of this approach is the patient’s increased autonomy and flexibility to carry out rehabilitation from home, especially in situations of lock-down and movement restrictions. In order to make the execution of repetitive exercises more dynamic and to motivate patients to perform them from home, in recent years gamification techniques, exergames, and serious games have been extensively used. In this context, and to increase the remote monitoring capabilities of therapists, this paper proposes the use of a language for the specification of exergames oriented to the definition, by therapists, of key performance indicators and mobility constraints adapted to the rehabilitation process of each patient. The sentences of this language can be processed by software, allowing the automatic generation of personalised games for rehabilitation. A case study describing an exergame for the upper limb rehabilitation of stroke patients is also presented.