Hey the steam controller was kind of a flop but I got one when they went on closeout at like $5 and it's actually pretty sweet. Very niche but definitely unique.
Just to defend this as an engineer (though not one that works with submarines in any capacity), using a video game controller might sound funny, but it could actually make sense vs. using a device of your own creation. They're highly replaceable, so you have an infinite supply of reliable backups to draw upon. It's not prone to design flaws in the same way a "homemade" controller would be. OTS devices are often designed to withstand certain conditions or modes of use, such as force or moisture or whatever else you anticipate in your environment. They're also widely used, so there are troves of publicly available information on them to draw upon. It might seem silly, but if I were building a titanic submarine YOLO ship thing, I'd probably use something similar.
Ask any serious video gamer and they'll talk your ear off about highly reliable hall-effect sensor joysticks and other such high-reliability parts (Cherry switches, etc. etc.) that kick the ass of cheap potentiometers + dome-rubber style switches (like found in a cheap-ass Logitech).
And such parts are available at... $50 to $80. Choosing a cheap-ass $30 piece of junk isn't even saving much money.