I would like to see a message of some sort appear whenever a unique or artifact item is destroyed, something like "A sense of loss comes over you", or "You feel the presence fade away...". That way, when a unique is spawned, you wouldn't have to search through the entire level for the item once all the enemies are dead, before concluding that it was destroyed in a barrel explosion or some similar fate. The player's character can already sense when a unique is nearby ("You feel there is something really valuable here!"), so he would most likely be able to sense when that valuable item is no longer there. I don't know how hard this would be to code, but if it wouldn't be too much, this would be a nice feature to avoid spending time needlessly searching. It would be especially useful in the later levels when, unless you have an extra Envirosuit Pack, it can take several minutes to search through the level because of all the lava you have to tread carefully around.