Friv games is a free online game site mainly aimed at children.
Friv currently have a 'Kill Covid-19' game which could be fun for your children to play.
Friv offer hundreds of games, some educational. Friv has been around for over 10 years and has a very easy to use interface, appealing to children. Colorful and bright.
If your children are getting bored then this may be the perfect solution. Let them have some fun on Friv while learning in the process.