The venerable Civilization series is one of the best turn-based strategy franchises in history, and the latest iteration is without doubt the best of them all. The base Civ 4 game improved on every element of its predecessors that needed it, and left the bits that worked intact – the result was a beautifully deep and streamlined strategy game that was as captivating as the original when it launched in 1991.

Like all games in the series, Firaxis was expected to release a string of expansion packs, promising new nations, new technologies and new units. And indeed, the first expansion, Warlords, did just that. It delivered precisely what was expected and we lapped it up with gusto, so it was understandable that we approached the latest expansion, Beyond the Sword, with a similar confidence. But boy were we wrong – Beyond the Sword has quite simply done the impossible and turned Civ 4 into the quintessential strategy game of all time.

Yes, BtS features a truckload of standard expansion fare like new nations, leaders, technologies and units. But clearly, Sid Meier and the boys saw holes in the core game that we hadn’t, and BtS features a couple of fundamental changes. First is corporations, which work similarly to religion, but provide commercial benefits when they spread into other nations. The second is a revamped espionage system, which makes spying far more interesting than the original implementation. In the latter, you now ‘invest’ in spying to accumulate espionage points which can be spent on covert missions against other nations.

But while those changes are welcome, they pale in comparison to the additional content in BtS. Take, for example, the Final Frontier modification, which turns the game into a 4X space strategy game with all new technologies, ships and game mechanics. Then there’s Afterworld, which puts you in command of a small squad of futuristic units in a post-apocalyptic world — no base building, just tight tactical gameplay and RPG upgrade paths. There’s also Fall from Heaven, which has you casting spells in a classic fantasy world, and if near-future combat is your thing, there’s the giant robot warfare in Next War.

If there’s one criticism we have of the new scenarios it’s that they vary greatly in quality. Some, like the Gods of Old scenario, work superbly, but others, like Final Frontier, feel like novelties compared to recent star performers, like Stardock’s Galactic Civilizations. That said, there’s nothing in the new pack that isn’t worth playing and each will keep you going for a week at least.

Combined with the tweaks and enhancements made to the core game, you’ll be able to squeeze at least another year out Civ 4. It’s a must for fans, but we recommend newcomers wait until a bundle pack arrives featuring the base game and the expansions.