I have created a simple 2D platformer for my Master's Thesis topic "in-game rewards and their effect on the player". I have also created a questionnaire in regards to your experience playing the game and the whole "in-game rewards" topic for my research. The game consists of 4 simple levels, where each level focuses on different types of gameplay.
I would be greateful if you could check the game out and complete the questionnaire (you can find the link to it in the description of the game). Thanks a lot and have a nice day.