By bad design decisions I mean like this.
It doesn’t have regenerating health, so you have to go to health stations to get your health back. Thankfully, unlike Half-Life, you can do this an unlimited amount of times.
But even with that, there should be no reason for a game without regenerating health to require you to LOSE health to progress the story. Because if you’re too low on health and can’t go back to a health station, you’re stuck. You have to go back to the last save point you did earlier.
That’s my biggest problem with the game, but it’s got a brilliant map system (you can move while looking at the map WHAT A CONCEPT) and I can feel the ingredients of HALO in it. You can’t jump, but you fall very slowly and have lots of airtime.
Enemy variety and gun variety are surprisingly good. Again, it’s got the foreshadowing of Halo. And the level design is very puzzle-like. I felt smart figuring out how to use the buttons and the platforming.
Halo is still better, but you could do a lot worse than Marathon. I’d recommend it. It’s free on Steam.