Probably one of the best 2D Metroidvania game i've played in these past couple years.

In Hollow Knight, you play as a bug-like creature exploring the underground world of Hallownest, from dimly lit caverns to jellyfish-infested jungles. Infested with bug-like npcs and enemies, the bosses in this game are great and their designs are unique for each one of them. Although the environment may be drag and grey, it matches the setting of this game rather well.

In terms of gameplay, this game plays surprising well. The controls are tight even though you are slightly limited to a jump and a strike (and the occasional dash). The "Swapper", one of the unique mechanics in this game involves the use of charms, once you are rested on a bench (the Bonfire of Hollow Knight) you can swap charms to increase your abilities or add new ones.

My main issues for this game is the excessive backtracking, without the compass charm to track where you on the map, the confusing level layout will make you lost very easily. Areas you have not explored before requires the purchase of a map purchased at the vendor in said new area. This forces you to search high and low and look at every nook and cranny until you find the vendor.

Overall this game is excellent in terms of gameplay and art design, if you like the Metroidvania genre, or even like the exploration aspect, this game is a must buy. The only thing I regret is not backing this kickstarter a couple years back.

Another game I would highly recommend is Ori and the blind forest.