Reddits gatordile2 has released a new update for the fan remake of Metroid 2, Another Metroid 2 Remake (also known as AM2R). This new patch adds a new difficulty level and some new enemies, fixes various glitches, adds/updates the 8-bit filters and improves some reported lag problems.
Source: N4G PC New Another Metroid 2 Remake update adds new difficulty level & new enemies, fixes glitches and more