We have 5DC,2 of our DC are disabled and since I became disabled health issues can sometimes stop us from being able to go out as much as we'd like.
Days that we have to be in the house we play board games,pictionary,guess who I am game(write a name of someone famous on a post it note and stick on another persons forehead and they have to try and guess who they are,for younger children you can make it cartoon charaters or you can guess which object you are,same idea just an object around the house/garden instead of a person or cartoon character ).
We play hide and seek.
Have a treasure hunt around the house,you can make an authentic looking map write the map out on a piece of plain paper and then brush with cold tea,put the "map" onto a baking tray and place in a low/medium heat oven,it should take under 10 minutes.
To make it look even more authentic roll the map up and tie with a ribbon.
We have movie and popcorn session,we make homemade popcorn with the children and sit and watch family movies together.
We play find and fetch them,we get the children into groups and tell them an object to go and find and we set a timer the first one's back with all the items they had to collect are the winners.
Some days we'll cook together and have themed evenings.
One of they're favourites is a Pizza and Sundae night.
We make or buy plain pizza bases and set out bowls with different toppings and the children top they're pizzas and we stick them into the oven for them.
Afterwards we set out sundae dishes,tubs of different flavoured ice creams,different sauces and toppings and everyone gets to create they're own ice cream sundae.
We do arts and crafts,we've tie dyed socks and t-shirts.
We got packs of 6 pairs of plain white socks for a few pounds and the white t-shirts were only £2 pounds each and the kits cost under £5 each,we managed to do 3 pairs of tie dyed socks and 2 tie dyed T-shirts for around £6 per child.
Paper can end up costing alot if you have alot of children or children that love painting and drawing alot but you can pick up whole rolls of wallpaper for £1 and let your children,draw and paint on the inside of the roll.They're great as well for if your children want to draw around each other or they're parents.
Easter time we usually make Easter nests,have an Easter Egg hunt,make Easter pictures,paint eggs and make Easter hats and bonnets.
For days out we find alot of the local museums really good,so many museums are free entry now and lots of them put on drop in sessions where you can go and do arts and crafts/play games/try on costumes.Some are free and you can just drop in others you have to book and some charge a couple of pounds per person for a make and take home session.
Parks and a picnic are popular with our children, sometimes we'll meet up with a group of friends and we'll all take some play equipment with us if there's space to use them at the park,things like a football,frisbee,a rounders set.
We check out our local leisure centers for any offer on for when the children are on half term,lots of them offer drop in sessions for free or for a minimal fee.Quite a few council run one's offer £1 swim sessions.