#13 - Theme Hospital (Kudos to Soulfly for guessing this)
Completing the "games involving managing units" section of my list is Bullfrog's finest hour. I'm sure you've seen me on the forums praising them time and time again for being my favourite company of all time, so I'm sure you can appreciate how much I love this game.
Theme Hospital just mixes in everything I love and expect from them. Micro-management is tweaked just right to always give you something to do but never be overwhelmed. The traditional Bullfrog off-the-wall humour is in there, asking you to treat 'diseases' such as infectious laughter; hairyitis and transparancy, caused by a range of reasons including licking the lids of yoghurt pots; eating pizza found under the cooker and prolonged exposure to the moon. Throw in a ridiculously hyperactive receptionist announcing every little thing about the hospital, and you've got a recipe for tonnes of laughs.
Just like with Tiberian Sun, I really cannot praise this game enough. Bullfrog just got everything they could've possibly done right with this game and it shines through as a great example of why they were so brilliant.