A Walk in the Dark is an artfully done little 2D precision platformer. It's good for a few hours of entertainment, and is recommended for its art style, including music, and enjoyable gameplay. On the downside it's too short and doesn't offer enough challenge to play for very long.
You usually control a black cat, named Bast, and less often the cat's owner, a little girl named Arielle, through 100 short but fairly tricky levels. There is no story to speak of - it appears that the cat and girl are separated and are trying to get back to each other, which is all the motive they really need. Your goals are to (1) not die as you make your way to the end of each level, (2) optionally complete the levels within a "par" time, collect a difficult-to-reach "shiney" in each level, and beat a few auto-scrolling levels without dying on your first attempt.
Without a plot, you might entertain yourself by identifying all the gaming elements that AWITD has borrowed (ahem, stolen) from other games. This is true both of its art direction and gameplay, although the game adds just enough of its own personality to make it feel like more than a knock-off.
Starting with the game art, the most obvious influence is Limbo, as the characters and landscape slide by in silhouette. But where Limbo was dark and violent, this game always stays light and fairy-taley, with your character's many deaths rendered with a rather artful puff of black smoke. The backgrounds come from any number of recent indie platformers, with bright contrasts and light blooms and generic "world" colorings. The game's music - tinkly piano - is unusually good, although after awhile the repeating themes start to wear thin.
If you've played Super Meat Boy, you'll instantly understand how most of the cat levels work: precise jumping, up to and including sticky wall sliding and avoiding spikes and spinning blades. If you've played any of the million games that incorporate an inversion mechanic, you'll recognize the girl's (only) trick, a gravity flip. If you played VVVVVV, you'll recognize similar tricky flipping challenges in later cat levels. If you played Bit.Trip Runner, you'll recognize the auto-scrolling levels. Unfortunately the game is too easy and too short to really stand up to any of these others - only the later levels were really interesting or challenging, and the game could have been more satisfying if it had more thoroughly explored its own interesting mechanics.
Overall this is an enjoyable, but light, little game.