I'll probably repeat this Top 5 exercise in a few months time once I've had a chance to play more games, I would imagine this one will be upwardly mobile during that time as it is phenomenally popular on BGG and I've only played it three times, so I'm not fully up to speed on it yet. So without further ado:
Caylus by William Attia is fairly heavy strategy game, themed around the building of a castle. Players compete as foremen, each trying to gain the most credit for the castle's construction. Initial impressions were not that favourable: an awful box illustration and nigh-impenetrable rules, however the board design is quite clever with an integrated scoreboard, and a track ordered in activation order, and as ever with the Eurogames the pieces are lovely little stained wooden numbers.
Once the game gets underway, players take it in turns to place workers in buildings to gain resources or other benefits. Only one worker may be placed in each building (with a couple of exceptions) each turn, so turn order is important. Fortunately, one of the buildings allows you to move up the turn order by placing a worker in it. Each player only has six workers, and placing a worker costs money (starting at one dernier, but rapidly increasing as players pass), so your options are limited in three dimensions, as other players fill the other buildings, you run out of money and you run out of workers.
After the every player has passed you each get to move the Provost, a mechanism which allows to to disable the more advanced buildings. Moving the Provost costs one dernier per square, moving him forward makes more buildings accessible, moving him back disables buildings instead. Players try to place the Provost in a location where they can activate all the buildings they have workers in, while denying as many of their opponents as possible. In addition, simply moving the Provost forward will speed the end of the game, while moving him back can delay it - allowing players an opportunity to end the game at the time most opportune for themselves.
Once each player has had a chance to move the Provost, the buildings are activated in order, and each player gains the resources or other benefit from the buildings they had workers in. The order is important, as I've already fallen foul of it a couple of times, placing workers to perform an action, safe in the knowledge that I've placed other workers to gain the requisite resources, only to realise later that the action worker is activated before the resource worker has collected the necessary goods. There are buildings to let you build other buildings, gain resources, trade resources for cash, gain cash, trade cash for resources, change the turn order and several others. The options throughout the game are manifold, leading to plenty of interesting strategising. Buildings come in several types, wooden(basic), stone (more advanced), residential (earn you cash) and prestige (contribute significantly towards winning the game). Each time you build a building you get a small VP bonus, and every time another player places a worker in one of your buildings you get a further VP, so buildings are a potentially winning strategy.
After building activation, all those players who placed a worker in the castle get to deliver batches of goods to the castle building site, contributing towards one of the three stages of the castle. Each batch must consist of three different goods, and you may deliver as many batches as you have goods. Batches earn you a significant number of VPs (5, 4 and 3 respectively for the three stages of the castle), and in addition, the player who delivered the most batches this turn gains a Royal Favour (more on these in a minute). When each section of the castle is complete, players may gain additional favours if they have delivered enough batches to that section, or lose VPs if they have delivered none.
The Royal Favours mentioned above come in four flavours: Cash, VPs, Resources and Building. Every time you gain a favour you may increment your marker along your choice of one of the four tracks, with successive favours on a track giving a larger reward, encouraging players to specialise on one or two tracks. The favours are a nice mechanism which allow players to choose their reward for building the castle. Short on cash? Gain money favours. Getting creamed on the scoreboard? Gain VPs.
From the three games I've played (two 4-player games and a 2-player game) it is clear that Caylus is a very good, and very complex game. There are still whole realms of the game I've yet to experience, and rules which I've failed to get right, but there are so many options and strategies that the game certainly appeals to me and offers plenty of replayability. I can easily see this becoming a favourite as time goes on. With limited experience I give Caylus a solid 8 on the BGG scale.