What is the best option for playing LAN games over the internet these days?

Hamachi appears to still be a thing, but I would prefer something open source.

Tailscale sadly doesn't support multicast, which I'm assuming most games use for LAN discovery.

ZeroTier maybe?

Tappers – ergonomic, cross-platform TUN/TAP interfaces for Rust

That's awesome. What sort of changes have they made? I feel like that's got to be a tricky line to walk for a classic game.

I thought about almost this exact thing recently. I hope we're able to keep the best games running forever.

For games that are fun I think you can leave in balance issues and even features-not-bugs. It's trickier for things like netcode bugs that are purely a negative.

Really grateful Id release their source eventually. Really hoping the same will happen for AoE2 someday.

Check out Voobly. That seems to be a pretty big hub for people playing the original games, I think mostly patched versions of the originals with some nice features.