Crucible feels really hard?

[Vanta]

Playing as imperial guard on standard difficulty with double resource gain, finding i'm struggling a lot. Enemies seem to just break through my defenses fast

[DasaKamov]

I'm not familiar with Crucible - assuming it's some sort of mod?

Regardless, the "double-resource-gain" is likely the source of your difficulty, as it lets the AI spam double the amount of units at you at any one time.

[fuggles2k]

It's an alternative to ultimate apocalypse.

[Boonkie]

It's like ultimate apocalypse but with more. It's so hard that there's a easy mod for it. It makes the campaign more fun
https://www.moddb.com/mods/the-crucible-mod/downloads/crucible-campaign-easy-difficulty