Square Enix's action RPGs NieR:Automata and NieR Replicant ver.1.22474487139... are currently on sale with a 60% discount on Steam. The current prices for the two titles are ¥109.6 and ¥143.6, respectively.
The story of NieR:Automata takes place in a distant future where machine lifeforms have taken over the Earth. Players assume the role of the android 2B, tasked with reclaiming the planet.
NieR Replicant ver.1.22474487139... tells an earlier story: the protagonist embarks on a journey to save his younger sister Yonah, who suffers from an incurable disease. This title is a remaster of the 2010 release NieR Replicant, featuring upgraded visuals and other enhancements.
The NieR series is a spin-off of the Drakengard series, also published by Square Enix. Although the two series share some thematic elements, their stories are not directly connected, so you don't need to play Drakengard to understand the narrative of the NieR series.