The West Seattle Y just added an indoor soccer program for almost-4 year olds, but it is during the day. There are evening program for ages 4 andup. It’s way cheaper than lil kickers, even for non-YMCA members. There are tmbling classes at the Jungle Gym in Burien. If you’re a member of the Y, you can also get balls from the front desk and play in the gym or a racquetball court.