I read somewhere, what reward was for winning chess game (a 6 extra tiles in your inventory), i can live without extra Inventory upgrade.
And going into second-to-last level (Security), a pretty big spike in difficulty.
First, a respawning there has been disabled (so if i die- it's game over); Second, a powerful enemies are present here. Remember those Fliers, armed with Bio-stuff in Storage? Now they have missile launchers! Luckily, they were only in this deck. Elite Cyborg Assasins, Mutated Cyborgs and Security Bots Mk.2 (especially in Repair Bay)etc. At least reducing security level to 0% was easy.
And FINALLY (after several tries) got rid of Diego, for good this time (dealt finishing blow with Rapier, for achievement). Time to say goodbye for Citadel Station, it was a pleasure to visit it.