UPDATE 6/29/2018: After attending ISTE 2018 in Chicago this past week, I learned another idea for student game submissions. Using a Google Chrome extension add-on, Screencastify (https://tinyurl.com/ks3rspn), students will record themselves playing their game and submit the video as a part of the assignment. That way, as the teacher you can watch your students play their game the way it was meant to be played.
My students thoroughly enjoyed developing their own video games using the FlowLab Video Game Creator website (flowlab.io). Students can create a game right in their browser, so you do not need to install anything extra. I am attaching the rubric I used with the assignment. I based the rubric on the Video Tutorials for their final product. (Go to Help > Video Tutorials) My students worked through about two video tutorials a day. The “teaching” part for me took about one week and I gave them a couple of days to work on the assignment after that (most were working on developing their games from day one). I am considering upgrading our account for my students to put their games in APP form! Thank you, @flowlab.io!