There isn't any patch available for now.
— PrestaShop (@PrestaShop) November 22, 2017
To get access to your back office, we suggest you rename the gamification file. You should find it here: modules/gamification.
Other possibility: you can also delete the line in your database:
ps_tab >> a module = “gamification”.
https://goo.gl/EO0ad1
https://goo.gl/xF8heB