Kalypso recently released the fourth DLC pack for its excellent city-builder, Tropico 4. The challenging scenario in this five-dollar add-on is easily worth the price of admission.

I'm a huge and unapologetic fan of all things Tropico 4, but the one area that has always been lacking is challenge. Completing the campaign or a (unfortunately barebones) sandbox scenario is not difficult; the only pressure on the player is to compete for a higher score. The Megalopolis scenario is the first exception to this rule.

The simulation's generous rules mean that every Tropico island is always climbing an upward spiral of growing prosperity and happiness – player skill really only impacts how steep the incline is. Megalopolis puts this front and center, pitting the player's island against an offscreen rival city in a race to complete objectives and grow their population and economy. Unlike the occasional other Tropico scenarios that include a fail condition, though, Megalopolis is tuned more tightly. I couldn't be happier to finally be pushed into honing my city-building craft.

Megalopolis also throws a simple twist into your island's development that dramatically changes its trajectory. China constantly offers to send big batches of immigrants to Tropico for a relatively small payment. As population growth is usually the limiting factor for any island, this lets a skilled player jump-start his economy in a huge way – provided you can provide the housing, food, and social services that all Tropicans require in the needed quantities.

The net effect of the always-tense race and the exploding population you need to keep up is the kind of engrossing push-pull dynamic I've always hoped Tropico could achieve but which it has never consistently managed. I'm frantically constructing as many of the new Conventillo buildings as possible to house my imported workforce, desperately trying to industrialize my production to kick my export economy to the next level, and all the while placating my screaming faction leaders just enough to keep them from rioting in the streets.

And then three tornadoes descend on my poor city and everything goes to hell.

I'm as impressed with Megalopolis as I am with the previous Tropico 4 DLC scenario packs (Plantador and Pirate Heaven are both excellent, though the non-scenario Junta and Quick-Dry Cement DLC packs are lame). I heartily recommend all three as worthwhile add-ons to what is already the best city-builder in years. Five bucks for a single scenario sounds like a lot, but these lengthy missions are all moderately replayable on top of their basic several-hour entertainment value. 

Megalopolis is available right now on PC, and coming soon to Xbox 360.