How interesting that is considering the last baby shower I went to the father to be acted as the bartender. And the last wedding shower I went to the groom and father of the bride were also there acting as bartenders and social butterflies.
On the other hand if there's to be a couple's wedding shower it's not a traditional boring lame shower either IME. I also can't imagine a shower being a poker night..a bacherlor party sure but not a shower so I'm personally not convinced the groom would be the one behind pushing an admit fee for this purpose. They could have just had the guys hang out doing their thing and the women doing their own thing however sexist that is rather than have people pay to attend for the privilege of playing games. But hey I did say I was unfamiliar with this custom but I sure don't know any guys who would swap out an actual poker night with "hey honey let's just charge people instead".
Similar experience here. I just went to a Couple's shower (very common and what they are called here) yesterday. It was more of a fun brunch with gifts- Bloody Mary bar, Mimosa bar, catered Private chef meal- a fun Saturday morning for people who love to brunch that honored an engaged couple. It was held at the engaged couple's new and mostly empty house. Also nice since we all got to see it and there was plenty of room for the setting up of tables and bars as it isn't fully furnished yet. Before anyone clutches their pearls, They didn't host. It was just at their house.
DD and DSIL were given one in 2019. A big BBQ Pool party, with yard games, pool games, lots of hanging out. The gifts weren't even opened at the shower.
Recently, on the same day as DD's baby shower, a group of DSIL's friends hosted a Crawfish boil. This is something their friend group, with SIL normally hosting, do at least once every spring. This time his friends hosted. It was men only (DH and DS went) and it was Crawfish, beer, cornhole, and hanging out until late into the evening. All the guys attending brought boxes of diapers as gifts. I doubt they need to buy diapers for 6 months or more.
Honestly, I think millennials are changing the norms of showers, weddings, and the like. They are much more informal and anything goes with fewer rules. I'm here for it.
As far as the original question, I have never heard of being charged to attend. I would bet the cash goes to the couple and the games are "just for fun." I would probably also take a card with cash, just in case, since it seems that you want to go. I wouldn't let it keep me from attending if it sounded like a good time. I would deduct the $50 from whatever I planned to spend on a gift.
That's just a total guess though because I've honestly never heard of anything like you're describing. Very, very few J&J showers here and the ones I know of having happened are like a poster mentioned up-thread; backyard burger-and-beer afternoons with friends/family of both members of the bridal couple attending. The "expected" gifts were just regular shower stuff.
