Every day I get more impressed at how many games have come out of Steam's early access program. Some have been giant disappointments while others such as Portal Knights, developed by Keen Games and published by 505 Games, do so well that they end up coming to consoles.
Positives + Very easy to get into; + Building stuff is fun once you get the hang of it
Negatives - Crafting could be more explanation; - Skills only drop from enemies, can't learn them