[susan53]

At that age they can't do organised games. Just play with them like you would in their own language, using the toys they already have - but talk to them naturally in English as you do it. Look at picture books with them , pointing to things and saying eg Look, there's teddy. Teddy's having breakfast. Where's Teddy's mummy? There she is!; build towers out of blocks commenting on what you're doing : Ok let's put the yellow block on the red block. There it is! Where's the green block? Can you put it on? Yes! Oh - you knocked them down! Whatever toys they've got, play with them in English as you naturally would with any child of the same age. If you're not teaching them in their own homes, ask the parents to bring enough toys and books with the children to keep you going for the time they're with you. remember - they don't have to be english books. it's just the pictures you want. books for kids of that age can be used in any language.
Don't expect the children to understand any concept which they don't understand in their own language - eg if they don't recognise colours in their L1 they won't yet be ready to do so in English.
Children of that age learn language from being exposed to "here and now" conversation - language which is very concrete in its reference to the things around them, as in my examples. You can find out more about it by Googling motherese or caretaker speech. Just expose them to as much of it as possible - you'll know they understand when one day you say Where's Teddy? and the child looks at teddy before you point to him. Don't expect them to speak - if after quite a while you get single words, that's fine.
If you want more ideas, just find any parent with a child of the same age and observe them playing with the child for an hour or so. What they're doing is exactly what you should be doing - but in English.