Changelog for Patch 1.015 (added 19 April 2017):

Gameplay improvements:
- “stuck in holes” fix - disconnected exits will no longer snag you
- subtle backlit slugcat in low visibility swimming situations
- quicker turning around in tunnels
- larger lung capacity while swimming
- nerfed the more intense waterfalls in Shoreline to prevent repeated drownings
- more pearls near Scav tolls in Garbage Wastes
- more food in central Garbage Wastes
- more food in central Shaded Citadel
- more karma flowers in world
- karma gate requirements on the Shaded Citadel, Drainage System and Underhang side were lowered to prevent players becoming stuck in challenging regions
- food / karma flowers regeneration now ticks forward on deaths (helps eliminate stuck / starvation situations at low karma)
- players will now keep map progress between deaths (Id say 99.5% of people asked for this)
- map now features gate karma symbols and shelter icons when locations are discovered
- karma depletion on game exit removed if done within 30 seconds of sleep cycle
- full karma drop on exit bug fixed (that was a brutal one, sheesh!)
- intro cinematic is now skippable by holding start / esc
- for players having issues with Grey Screen of Death and starting the game from sav files, you can now entirely skip loading the intro by holding "s" when pressing "New Game." hopefully this helps until we have a real fix!
- many many minor room fixes

Stability improvements:
- map loading bug fixed (was causing the corrupted savs, ugh)
- gate crashing bug fixed
- assorted stability improvements

MalwareBytes flagged and quarantined the gog rainworld 1.0-1.015 patcher as Ransomware Generic Agent.
Can someone look into why it is that MalwareBytes thinks the installer contains ransomware?

To add to what Judas said - I suggest you submit the file to them, explaining the situation and context.

FWIW, I did a scan with the free version and sigs updated today, it didn't find any problem with the file.

Changelog for Patch 1.5 (added 13 December 2017):

Main new features include:
- 2 new playable characters, corresponding to different playstyles and difficulty:
THE MONK - “Weak of body but strong of spirit. In tune with the mysteries of the world and empathetic to its creatures, your journey will be a significantly more peaceful one.”
- THE HUNTER - “Strong and quick, with a fierce metabolism requiring a steady diet of meat. But the stomach won’t be your only concern, as the path of the hunter is one of extreme peril.”

New Local Multiplayer arena modes:
- COMPETITIVE - Up to 4 player competitive mode. Catch bats and spear creatures (and each other!) for points. Players can choose from rooms that have been unlocked from finding yellow level tokens in the single player campaigns. Increasingly diverse wildlife will populate these rooms as you discover more blue tokens.
- SANDBOX - Up to 4 players, put together custom scenarios using rooms, items and creatures unlocked from the single player campaign. Creatures and items can be placed in a room as desired and then played through with a various point values, etc, attached. This mode is to experiment and learn about the behaviour of creatures players encounter in the world.
- Over 30 new multiplayer levels to be unlocked!
- Updated bestiary, with a host of new creatures and items available to every character. Escape from new and dangerous predators! Feast on delicious new prey! Or perhaps... bond with new friends?
- Plus of course a host of new secrets to be found, new strangeness to experience, and hopefully generally a much smoother Rain World experience!