Serpentina (also called Hisss by Gamewright games in this country) is a cute little luck game that involves making sets of rainbow snakes. It's easy for children and not too mind numbing for adults either.
Serpentina is by Amigo games and is advertised for 4 years and up. If your child understands taking turns and basic colours they can play this game. My little guy was playing this with help from 2.5 years old. I say help, but it was basically a constant reminder that he only got one turn at a time. By nearly 5 he can describe it and play with other children his age. So really this game is great for kids playing together because of the heavy luck and simplicity.
Game Play

It's slightly cooperative in that if you draw yellow/orange you attach it to any snake with available yellow or orange slot. However this can emotionally become challenging for little ones as sometimes they see a snake as "thier" snake and then someone else completes it and it goes away.

Review
As you can see I do love this game and I love that he can now play it with other kids basically without me. The cards are thicker then normal playing cards so we have played this a lot and have loaded it out to friends without it ever being damaged.
However I do still feel I need to be there while he plays with others his age in case anyone gets upset about loosing a snake they thought was theirs. I think by about the age of 6 I wouldn't need to keep such a close eye. My kid and his best friend play this regularly with no issues as they are used to it together. It isn't in my top 6 and that's mostly the reason why, it's not quiet cooperative and not really competitive so it isn't perfect for us- although it might be perfect for your kids!
You can find it in this country through the name of Hisss by Gamewright games (which is an american games company). I know that my local games shop usually stocks it when they can get a supply from the USA so it is worth calling and asking your Friendly Local Game Store first before heading online.
As of writing this in July 2019 it looked like Hisss was hard to get a hold of (maybe out of print) so before going and spending a bunch of money on this call your local shops as they might have one lying around. Or check out Board Game Geek and see what prices are roughly going for there as then if its more then about £15 or so pounds its likely its still out of print/stock.
As of writing this in July 2019 it looked like Hisss was hard to get a hold of (maybe out of print) so before going and spending a bunch of money on this call your local shops as they might have one lying around. Or check out Board Game Geek and see what prices are roughly going for there as then if its more then about £15 or so pounds its likely its still out of print/stock.