Before playing top down 2D shooter Nuclear Throne, I could not fathom why anyone would play a roguelike. Now I realize that other games made me think that way.
The trend in shooters (and most games really) since at least COD: Modern Warfare is to add some sort of progression mechanics. We like it when the numbers go up. That's where my expectations have been set. Progress is guaranteed and you can never go backwards, only forward at different rates.
Nuclear Throne is not like those games. It does have experience in the form of little green rectangles called Rads that you find in the level or retrieve from dead enemies. Collect enough Rads and you gain a level. Gain a level and choose a single upgrade which stacks on top of others you may have. If you die, you lose everything. This, to me, sounds profoundly unappealing.
What keeps me clicking Retry at the end of each run for the Throne (I have yet to peep it) is the low friction and addictive feel of the game. You can be right back in the thick of a firefight in 5 seconds. The guns are varied and fun to shoot, and the procedurally generated levels have you itching to see what the next room will look like. It's also simple, which is great. You have one special move and can hold two guns at a time. I don't want to spend a bunch of time in inventory screens if everything I'm looking at could be taken from me in an instant.
There is certainly a slot machine aspect. Which weapons will be dropped in each area? Which upgrades will you have to choose from after leveling up? Will you spawn near a den of radiation-spewing scorpions or a single unlucky grunt? All of these things affect your chances of surviving to the next round, but they never seem to outweigh the influence of your own skill at the game.
Your skill is still the only thing that will allow you to reach the end. The developers at Vlambeer are boldly asking you to, in the common parlance, git gud. A lot of big games that need to sell well literally can't afford to ask you to do that. That's part of the reason this resurgence of difficult games is taking place.
Nuclear Throne has shown me that there is still a place in my life for hard games. The minute-to-minute action needs to be engaging, but not overly complex. Most of all, this type of game needs to do what other games only simulate with ever increasing numbers. They need to give you the feeling that what you are doing is very difficult, but you're getting better all the time.