Nzoia river basin county governments barely cooperate in water resources management to jointly increase the basin's food and energy productivity levels, due to limited trust. In this paper, we propose a game-based approach that can be replicated in any river basin, to assess trust and collaboration processes. In particular, we used the pre-game, in-game, and post-game assessment results to assess the relationship between Cooperation and Competition; Trust and Trustworthiness; Trust and Distrust; and (Dis) trust, Complexity, and Uncertainty. The initial assessment of respondents' propensity to trust (PTS) was divided into two variables (trust and trustworthiness) while adopting the unidimensional view of trust and distrust. We later examined whether we could separate the two constructs using a multidimensional scaling (MDS) technique known as the ALSCAL procedure. There are potentially significant results. Namely, that: trustworthiness and trust are not complementary; both cooperation and competition coexisted and increased throughout the game; more profound complexity and uncertainty led to an increment in trust, and reduced complexity and uncertainty led to a decrease in distrust. Based on the results and discussions, we provide recommendations for further research on trust, trustworthiness, and distrust in the river basin management context.