Choose two people to be ‘the sticky alien’.
They join hands and run around trying to tig people. When they do, the person caught becomes part of the sticky alien. The three people have to hold hands.
When there are four people holding hands, they have to split into twos.
These two pairs continue trying to tig people, and having them join on until they get to four people again, at which point they split into twos.
This continues until everyone has been tigged.