We let our 2yo cook eggs. We break them, and he whisks them with a fork/small whisk. We hold him up so that he can open the microwave door. We put the eggs in and show him which buttons to press and he gets it going. It takes a while, but he LOVES it.
An off spin of this is that he love whisking things. He spends hours whisking up water and pouring it from one cup to another. My mum also got him some stainless steel teapots from a cheap second hand shop, and he spends ages pouring water from one to another. This is a great game for him to do by himself.
Also we've put a potplant pot full of sand in our kitchen for him to dig in when the weather is bad outside.
Also, he LOVES plastic golf clubs. We play outside if poss, but if the weather is bad he can play in the house (with pingpong balls). Sometimes he plays on his own. Sometimes we hit the balls back to him.
We also have an old whiteboard that my brother was throwing out, and we put it on the floor and spend ages drawing on it. He draws lots of sqiggles and tells me what he is drawing (amazing the things he comes up with). I also draw whatever he wants me to (not very good, but he appreciates it).
He gives us lots of "concerts" playing "his" music to a cheap toy plastic guitar.
He loves to help with any household chore, such as vacuuming, making beds, dusting, watering plants, feeding the cats.
Rough and tumble on the floor - tickling him, putting a pingpong ball down his shirt (of course he then does that to us), making a tent/tunnel in the bed (with our knees) and he crawls into the "tunnel" and out the other side, making a tent with blankets over furniture, having a "picnic" (even inside) with fruit etc. Going swiming (in the local pool, or the bath with his toys)