Huge but not overwhelmingly, a classic TBS!
In Europa Universalis there are more than 1500 provinces to conquer, at a believable pace. You can play as any European nation that was on the map from the late 14 hundreds to the late 17 hundreds. So, yeah, it's a large game, a diverse game, but, since it was based on a tabletop game, it is also (almost!) immediately accessible. At least for reasonably seasoned gamers it should not pose any huge difficulties, as it plays in the style of most top down war game strategies. So, you can play both by using military force, or you can choose to go for diplomatic relationships or, better still, you can choose to go the way of the colonial wealth acquisition, by colonizing new areas and spaces of interest. Therefore, Europa Universalis is a game that is sure worth its salt, for those that love the idea of Settlers of Catan for instance, but would like that kind of mix inside a more complex game, say Civilization. Yep, it's a combination of both Europa Universalis, and it is also a sufficiently original game in its own ways, which is also pretty great as well. Also, graphically it works great, which only adds to the experience, so, if you like the ideas it proposes, give it a go!