This question has been answered by BobRay. See the first response.
Hi maybe I can get you started.
Signup-login is handled by the login extra, which is a bit old and clunky but works well once its deployed.
For stats, I think you would need ClassExtender. Modx by itself doesn't handle a lot of user info or handle it very well.
For stats, it also depends on what you want to show. Any idea about it?
For signing up for events, that seems easy enough, although I don't know precisely how.
Credits means in-system credits or link to a payment system? Using a payment system isn't too hard, there are some solutions. But an native credit system within your community might be a little involved.
If you extend the user for stats you can store the credits as well, no?
For the events there are a couple of extras, but I haven't used them and I'm not sure if you link it to your users. You could create your own event functionality as a custom extra (https://rtfm.modx.com/revolution/2.x/case-studies-and-tutorials/developing-an-extra-in-modx-revolution) or using MIGXdb (https://rtfm.modx.com/extras/revo/migxdb/, haven't used this myself) and link users to events.
MIGX is a reliable, full-featured extra and can do a lot of things, so that might be a good place to start.
I can definitely imagine that the register button of the event could be active if the user has credits, but I am not sure how to take the credit from the user when registering. It can't be that hard, though.
Also, do you want the credit taken just by registering? What if people change their mind or something.