We switched to a new corporate system quite a long time ago: no obligation, high frequency, a certain topic and - fees. The company compensates from 50 to 70% of expenses, the rest - employees are discounted.
At first, it was an experiment, and not even quite a corporate one - say, let's go to karting all together. Having collected feedback, we got: what you pay for (even if part of the price) - is valued much more than free alcoholic beverages (although no one canceled the alcohol).
Reduced costs for the company + partial coverage allowed to hold such events more often (in summer - every month!). We highly recommend it.
Front-end: $25
Back-end: $25 (PHP), $35 (JAVA, C#), $35 (Ruby, Python)
Analytics: $35 — $45
Mobile: $30
Design: $25 (designer), $35 (Art Director)
DevOps: $30
Testing: $20