AAA games tend to make most of the headlines throughout the calendar year. However, it can be argued that some of the best and most unique gaming experiences come from studios without the backing of big publishers. Independent developers have a great deal more freedom in defining what they want their game to be, and cater towards more of a target audience than the general public.
As the indie scene has evolved over the years, so has the quality of the games coming from it. There is a steadily growing financial payoff in going indie, and although it's still undoubtedly a riskier business venture, there are more and more developers making the jump, so the competition has become increasingly fierce.
This list does not necessarily consist of games with concrete release dates, as delays and uncertainty are the norm among indie titles. However, these games have at least been slated for release in 2015. Just bear in mind that this is all subject to change.