There's not much here, but you know what? What is here isn't poorly made. I feel like I detected some intelligent spawning of new lives as well as some targeted spawning of obstacles to keep me from getting comfortable. In a more complex game, I'd probably point out that it can often be hard to pick out the red outlines, but I feel like you did a gererally good enough job making them look threatening on their own that it wasn't an issue.
My biggest piece of advice for improving this would probably be that you could have ramped up somewhat more quickly. I'm a big proponent of giving players lots of warm-up time, but it was something like 2+minutes before I was starting to sweat, and most of the time before that was somewhat unstimulating.
In any case, it seems like you decided to make something you knew you could accomplish in the time given, and came out with something fairly polished for what it was. Well done!