It's only hard if you actually try to engage with all of the game mechanics.
- Play as the Dutch to get their four-item capacity ship
- settle near Ore
- build only one or two cities, and make them as populated as you can. Wagon train food and raw materials in if you have to.
- produce Tools and Guns, nothing else.
- Early on, sell shiploads of basically anything from Europe to the tribes to jumpstart your economy. You don't need any other dealings with the tribes or other Europeans.
- Put your carpenters to work building fortresses, universities, and cannons.
- Once you have a university, start training up soldiers. Clear all special skills not involved in growing food or producing guns so you have an large number of civilians to train up.
- Put a tall stack of professional soldiers and cannons in your fortresses.
After that, play Civ 1 and follow the chariot swarm strategy. I forget the exact strategy, but it's something like this:
- build your cities only two squares apart
- research only until you can build chariots, then set Science to 0%. (This takes all the fun out of the game for me, but winning on Deity mode is nice too)
- alternate between building colonists and chariots only. I think you build barracks as well
- build cities until you have a dense network of ~50 closely packed cities, each very small. Then churn out chariots.
- swarm everyone else with chariots ASAP. Hope that every enemy is reachable through dry land, or you're cooked.
You can beat the game with the max number of computer players on the highest difficulty this way... if your chariot swarm doesn't cause a buffer overflow.
- Research only towards monotheism and swarm with crusaders
- More interesting variation to break the game: go for republic as soon as possible, only build cities near water and other high trade squares. Put luxury to 80% and max out trade in cities by putting production to water/max trade squares. Build temples, market places and aqueducts and reach 1M population well before 0AD. Once population is maxed, put tax to 80% and instead of building, just buy what you need including enemy cities and barbarians. This leaves you a bit vulnerable, but when it works out it's a lot of fun. You can have massive cities built on isolated island etc.
E: Also, if you manage, build colossus, observatory and Newton's college in the same city. By the end you'll churn out new advances every 2 turns.
