For those of you whose machines do not have difficulty with precipitation scripts, here is a merged map of the scenario with both precipitation and the latest bugfixes from the final stages of Eternal development.
Unfortunately, some quirk of a few people's machines couldn't cope with precipitation, even after bugfixes were made, and so Pfhorrest ordered it cut from final release. Although the effect on most levels is subtle due to an A1 limitation on having 1024 objects, I thought it well worth the effort of maintaining. So, before I cut the lua from the main scenario, I created a branch to preserve it, and left the supporting alterations to the Shapes file in the main branch.
Naturally, you'll need to download Eternal 1.2, found here,, to use this map.
Then, download this map file, drop it in your Eternal directory, and select it in Environment preferences.
To test whether your machine can handle this, skip to level 13: A Friend in Need, and see if your framerate drops when you walk outside. My 12 year old rig gets 20 FPS with everything on, but some players have reported as little as 0.5 FPS with precipitation.
Since this is an altered map and not a plugin, it probably will not be compatible with save games from the official release, neither with co-op games where one player has the official and one player has this. For best results in co-op, both players should have the same version of the map.
Credits: Original rain and ember sprites by $lave and Windbreaker, respectively; Original precip code by Wrkncacnter, who borrowed heavily from Treelama; Eternal adaptation by Aaron Freed; Snow sprites and code fixes by Lia Gerty; Ashes are a palette swap of embers, fallout a palette swap of rain.