Most simulation games that exist are targeted towards experiencing and reflecting on Lean principles such as tact time, pull, Kanban, continuous improvements etc. The design phase in construction is characterised by information not being available, iterative work, specialized work tasks, and high uncertainty. The research aim is to develop and test a design simulation game that explains the design principles: lack of information, iterative work, and specialized work in order to let inexperienced people experience and reflect (ER) on the design phase. The method to develop the ER design game was to alter an already existing production sequence simulation game developed to illustrate one-piece flow. Action cards were entered into the game, changing work tasks and their sequencing as the game progressed. The ER design game demonstrates the difficulties in characterising and improving the design flow, but it does not show any methods to improve it. Lack of information, iterative work, specialized work, stop-start effects, and tact time issues all surfaced during playing the ER design game. The time frame for the game set was 45 minutes, which makes it feasible to incorporate in Lean method training.