Packet Path
The internet is a net: if one link breaks, the message finds another way.
Seven routers sit on a map, joined by eleven links. A packet — one small piece of a message — starts at router A and has to reach router G. It can only travel along a link, one hop at a time, and you choose every hop.
There is never only one way. Several routes work, which is the first thing to notice. Then a link snaps while the packet is already halfway across, and the packet carries on from where it is — it does not go back to the start. Then two links are down and one router is busy, so a hop into it costs double.
At the end you get to try to break the network yourself: cut any single link you like, one at a time, and watch whether A can still reach G.