Thank you everyone for your responses. Some awesome anecdotes and some heartfelt truths, plus some very useful references to research. The Ballmer curve is definitely going into the policy! There's appears to be a trend in this highly un-scientific survey of self-selected respondents that being lightly-intoxicated might improve your score, but irresponsible consumption of alcohol is likely to cause harm to your score, your health and community.
There are some studies on alcohol & creativity, such as by Benedek, Panzierer, Aljoscha & Neubauer, University of Graz, Austria https://doi.org/10.1016/j.concog.2017.06.020 who conclude that while there appear to be some benefits at certain stages of the creative process, there are drawbacks in others.
I'll keep looking for other interesting papers on the topic, but in the meantime here's some excerpts from my (draft) Host Responsibility Policy....
Ye Olde Hosty Responsibility Policy
The management and staff of Ye Olde Pinball Shoppe believe we have a responsibility to provide a safe and comfortable environment for pinheads to partake in the gentle art of pinball. To that effect we have instigated the following host responsibility guidelines…
Pinball flow states and intoxication
We are a pinball arcade first and foremost. The sale and supply of alcohol is secondary to our mission statement, but we acknowledge that for some players, performance improves after a drink or two, but degrades when more than mildly intoxicated. (citation needed) We have a limited range of alcoholic beverages on offer for those who find that light intoxication improves their creative flow state.
Non- and low-alcohol options
To further our goal of keeping intoxication levels low and pinball scores high, we promote and sell a range of non-alcoholic beers, ciders, sparkling wines and spritzes. We encourage patrons to try alternating between alcoholic and non-alcoholic beverages over the course of their visit. Free chilled water will always be available.
Pinheads of all ages are of course welcome to play pinball in our establishment, but people under legal drinking age will not be served alcohol. We request that minors are accompanied by a parent or guardian after 8pm.