Shots' behaviour against skies or wide areas...

[printz]

There's one thing left before full non-hacked Doom backwards compatibility: projectiles' and bullets' behaviour.

In Doom the projectiles blow up against floor/ceiling skies and sometimes vanish against solid walls close to skies (as in E4M6's blue key tower walls). Whether they blow up or vanish is an important issue if they're rockets or BFG shots. Targets' lifetimes depend on it.

Similarly, in Doom, the bullets may stop in flight, as in Doom 2 MAP12.

These little problems will desync demos (sure, unless there's a special measure :)) and modify the gameplay (such as when ducking from a cyberdemon who shoots into a low-ceiling sky, normally hurting you anyway, but with Boom not).

[Quasar]

Actually, though EE removes missiles that hit the sky during normal gameplay, this change is currently qualified on demo_version being greater than or equal to 329, so the change does not occur during playback of old demos, preserving compatibility :)

The error here is that I have not yet provided a compatibility variable to allow the user to toggle this behavior on or off during normal play :) There are a few remaining issues such as this with code that dates from very early in EE development. This change you speak of is one of the oldest modifications made to EE, and predates the change to SMMU as our codebase -- it was in fact first applied to the Eternity Total Conversion engine, a modified BOOM.EXE ;)