Mobility-as-a-Service is a solution offering a digital platform that integrates multimodal and mobility sharing services and offers them as single packages to the customers, which have a bundle of mobility services to use for their daily trips. This new mobility concept is regarded as a solution for reducing congestion and pollution levels by reducing private car usage. However, it requires a critical mass and density of potential customers to be successfully deployed. This is a great challenge for Luxembourg, where car ownership rates and mobility costs are the highest in Europe, and characterised by a scattered, low demand market. MaaS4All aims to develop models to analyse the MaaS system as a top-down approach, involving four key actors: the customers, the suppliers, the government and the broker. The company partner of this project, ACL, envisions itself as the national MaaS broker. Within MaaS4All, the University of Luxembourg will develop models and will integrate them in a toolkit that will enable ACL to estimate memberships, the resources needed to fulfil mobility needs, and to account for the impact of governmental policies. The project will involve two PhD students and a PostDoc to support the UL PI, together with ACL as non-contracting partner. After developing models analysing the interplay between the four actors, a game-theoretical approach will be adopted to study the system equilibrium in order to identify the conditions for successful and sustainable deployment of MaaS in Luxembourg and to develop the national MaaS platform managed by ACL. Different case studies will be used to test the solution and demonstrate its validity for different business models.