Vallorcine has a small playground near the train station and there is plenty of free parking on site.  There is also a basketball/football area just next to the playground.

In the summer months, the green space behind the playground and next to the river becomes a small paradise for children (and their tired parents), as a bouncy castle appears, a small playhouse, a ping-pong table and ponies too . . . And lots of tables, chairs and beanbags with parasols . . . With lunch, you can get an unlimited bouncing pass for 10€!  Pony rides are extra.