As j0e said, all you need is the Worms 2 Plus patch.
Opening ports is only needed for TCP multiplayer.
You can play without port forwarding using IPX thanks to the IPX servers (which you can browse, modify and select using the Address book button!), also ignore the "internet play is not supported with IPX" hint, it hasn't been updated.
Its quite normal for the servers to be empty. People usually plan games outside the lobbies, like on Discord for example.
As for the 'cool jumps in Worms Armageddon', assuming you're talking about the backflips you can indeed do them in Worms 2, but they were locked behind a cheat. Thankfully the Worms 2 Plus patch unlocks the backflip permanently, even in online modes