1) Playtime is for after hours, with friends and family. Ping pong's a fun game but it's noisy and disruptive when you're trying to get work done.
2) Don't care about your free food, I have a strict diet and don't usually eat lunch. Ditto free booze which is frankly a dumb idea (see 1). Free non-alcholic drinks is fine.
It's also a tax break in the UK. An employee and the employer aren't taxed on the provision of food but would be taxed on a bonus, so you can offer what amounts to £x worth of free food per year rather than (or in addition to) a cash bonus.
It's certainly not linear, though; I think it will be interesting to see what's better in the long run. It's obviously impossible to measure, due to unpredictable factors such as changes in industry and market and competition.
As a whole, though, I think people, especially in our industry, aren't stupid. Free food would certainly be a more competitive retention factor (than ping pong) -- barring that your company's biggest competitors in terms of hiring aren't also offering free food.
"Hey, we have a dysfunctional CEO, a runway shorter than the one at Hong Kong airport, and a legacy codebase that reduces the most experienced developer to a gibbering wreck. But look - we have foosball and whiskey tasting nights!"
Sure, it's a semi-facetious example. But I'm suspicious of job ads that mention things like foosball tables or climbing walls and other such frivolities - it suggests either a juvenile working environment or that the company has to provide gimmicks to entice people to work there because it doesn't have anything solid to offer.
The ROI on those "gimmicks" is huge - to my mind it's the company that wouldn't spend a small amount of money on something fun that's suspicious. That suggests a company that's more bothered about appearances/"professionalism" than just getting on with things.
Juvenile, shrug - I guess I like a juvenile working environment.
That's a rather strong assumption.