How about things for transforming the outside play house into other role play games such as:
- grocery shop (cash till, shopping baskets, play food)
- sweet shop (mine was given a sweet shop with weighing scales and play money, I extended it with a shop sign for the door, pretend sweets (dry pasta etc), little paper bags, price tags, toy mobile phones for home delivery orders, he used a little trike with trailer for deliveries) the sweet shop play was a huge hit at almost 4yo and still is, also friends love it
- post office (date and number stampers, ink pad, stickers, play stamps and tax discs, play airmail papers, play cheque book, lots of papers, pens, highlighters, envelopes and cards to write on, post box, postman outfit and bag)
Hamma beads
sticker books
mosaic stickers
musical instrument (ukulele maybe? ocarina is good for small hands)
dot to dot book
bike (mine got his for his 4th birthday - what a hit! started out with the pedals off as a balance bike. He's now got pedals on and rides without stabilizers 4.5yo)
jigsaws
board games (busy town, junior monopoly, frustration, connect 4)