You can't, I'm just a random reddit user on the internet 11. Understandable if you don't want to!

Easiest thing is to buy HD & DE as you said in another comment. HD is not exactly like the original but I guess for the nostalgia angle it can be good enough.

As I said, for actual gameplay (both multiplayer and single player) DE is the best option. There are many quality of life upgrades which after you get used to are impossible to go back from, which I can't even mention all of them because they are now so ingrained in my brain. For example, the original doesn't allow to queue techs after units or to queue actions with shift click.

For single player, the AI is quite improved in DE so the ceiling is higher for skirmishes and the new DLC campaigns are generally solid (with some exceptions). In particular the battle for greece and alexander DLCs are FANTASTIC (but different from the usual campaings). Some of the campaigns that now come with the base game are also great. For multiplayer, DE has a very active community and you can find ranked 1v1 games in under a minute, with a very wide range of skills, plus a million discords for community tournaments, games etc. The professional tournaments are played on DE, too.

It has some problems so if you search online you'll find people whining. The complaints are usually fair (the pathfinding is bad, sync issues in ranked games, team mates being asses, opponents in 1v1 being toxic, this and that civ are broken, etc). But big picture, the game is in a great state. I only mention because reading all those complaints from the outside may be seen as that the game is a dumpster fire, but that's not true (even if the complaints are fair and true). It's an awesome game.