Buy it on: Mac App Store
Price: Free (Lite)/$7.99 (Pro)
This enjoyable and simple game sees you constructing a bridge so that vehicles can get across safely. There is a definitive difficulty spike after the first couple of levels, but luckily, there is in-game help available if you get stuck.
Bridge Constructor is available as a free and paid version for Macs running OS X v10.6.6 (the most up to date Snow Leopard) or later.