Meyendtris is a variant of Tetris where the regular game mechanics (moving, rotating, and dropping the tetrominoes) are controlled by eye gaze. In addition, two passive BCIs influence additional parameters:
- The game speed depends on the player's relaxation and focus: the more distracted the player is, the faster and more difficult the game will be.
- An error detection mechanism to remove erroneously placed tetrominoes. When an error-related potential is detected following a tetromino drop, this tetromino is removed from the field. (Not currently implemented.)
- The concentration of the player's mental state is used to give rewards as he progresses in the game.
The first point means that players should not let their mistakes upset them -- it'll lead to only more mistakes. They should try to relax. At the same time however, the second point should work best when the player is properly focused. The third point, gives him the motivation to play the game better as he is rewarded when concentrated for a longer time.
Eye tracking ideally removes the game's dependency on manual input, which is often a bottleneck in original Tetris (increasingly so with increasing game speed). In Meyendtris, the game thus becomes a battle against oneself, balancing two mental states.
Meyendtris was developed during the IEEE Brain Hackathon in Budapest on October 8th and October 9th, 2016 by members of Team PhyPA: Laurens R Krol, Sarah-Christin Freytag, and Thorsten O Zander. Team PhyPA was sponsored at this event by Brain Products GmbH. This was again modified to add 2 other mental state as mentioned in point 2 and point 3 above by group of students as the project module of 13942: Foundations of Psychophysiology in the SoSe 2023.
Krol, L. R., Freytag, S.-C., & Zander, T. O. (2017). Meyendtris: A hands-free, multimodal Tetris clone using eye tracking and passive BCI for intuitive neuroadaptive gaming. In Proceedings of the 19th ACM International Conference on Multimodal Interaction (pp. 433–437). New York, NY, USA: ACM. doi: 10.1145/3136755.3136805
Meyendtris has been implemented in SNAP, which is based on the Panda3D engine. First, install the Panda3D SDK, available from https://www.panda3d.org. Panda3D will come with its own version of Python, and an executable called ppython.exe. The Meyendtris launcher (see below) calls this executable to start Meyendtris. Thus, make sure ppython is in the search path, or adjust the launcher batch file.
To start Meyendtris, launch ./demo/launcher-Meyendtris.bat or ./demo/launcher-Meyendtris.sh and proceed as instructerd. An LSL gaze stream is detected through this launcher method, failing that, an LSL cursor position stream (as e.g. produced by the app in ./misc/Mouse). This latter option should thus work with any eye tracker that can assume control over the cursor. If no stream is found, Meyendtris reverts to manual control.
Details can be found in the code of each module, located in ./demo/meyendtris/modules.