None of the stuff you had as a kid would be playable. The rules have changed, the figures replaced, old ones out classed, etc. GW rehashes so you have to buy new stuff constantly. They don't innovate (besides marketing/sales innovations).

Hasbro (wotc is subsidary) also rehashes, maybe more so. They're only innovations are sales and marketing based. They recent innovations online portal, 4ed and gamma world have flopped hard.