Any guide on artifacts/letters/secrets
 

etc etc.?

Or what can I check how many letters/secrets I have found in a level?

After completing each level, you can see your stats, including number of found letters, artifacts, etc.. So you can see whether you collected them all or not.

Well, that's the only time.

But games like Painkiller let you see the statistics at level-selection screen.

I have to admit that Painkiller is extremely friendly with item collectors like me :)

i'm making a video on fortress secrets
it was hard to find the last one (u must go back in the level by making a mega jump)
if u have any question on this level....

Do you have videos for secrets in other levels? or any other related information?