well, if we’re sticking to scummvm, they offer some free games on their site: scummvm.org/games/#games

the freebies are in general fairly old (like early-to-mid 90’s dos stuff), but work fine on scummvm, hence they’re offering them there. AFAIK all of them are controlled by mouse only.

Not all of them are suitable for all ages though.

Flight of the Amazon Queen is a story set in 40’s, about a pilot for hire and his small plane crashing into the amazons while transporting a movie star. Overall theme is cartoony/goofy/comedy, with a bit of juvenile humour ( by modern standards). There are some things some could find unsuitable for children, I guess.

• rubber breasts, used in non-sexual way to build a costume to fool gangsters
• the “bad guys” are essentially ww2 germans (but not referred as such, iirc their faction isn’t even given a name, I think)
• some alcohol & tobacco references
• very mild innuendos.

Beneath a steel sky - postapocalyptic oppressive world, although a bit cartoony/comical and oddly british considering the story takes place in australia. Banger adventure game but does contain few violent deaths. I played this during my early teens, but I wouldn’t suggest letting very young kids have a go at this.

The rest of the games on there I either haven’t played or can’t recommend.

But, since you asked for games for kids to learn to use mouse, I suspect the kids in question are like 5-7? These 2 games aren’t probably for them yet.