I hit three bonus symbols almost immediately and figured that I was only getting the free spins from the crazy low win I received from that spin, but it turns out the game only pays out 1x your stake even for all five bonus symbols... very strange. Still, the bonus itself sounded good as you get an unlimited number of free spins, up until the point that four additional wilds have been added to the reels by way of the "antidote" symbol on reel three. I found this feature quite frustrating though as when the antidote symbol does land it converts all of the corresonding symbols into wilds AFTER you have already been paid for that spin, which I found both confusing and a little tight as well. You get just one extra free spin with all four additional wilds active too, although I guess you can't complain too much as you have probably had plenty of free spins before this point - I had 22 in total from my very first entry into the bonus, although I won just 20x my stake from the whole lot.
And I guess that's my big issue with this game - it really doesn't seem to pay out very well and my balance remained pretty static throughout over 400 spins on the game. The overall RTP is almost 97% and I got the impression this was one of those that would just suck you dry slowly but surely without ever really having much chance of a big win.