Demonic Spiders: Vladic knights on planet Necryptos. It is almost literally impossible to get past them without a vampire hunter mecha. Whereas previously most other vampire mooks were difficult, but not impossible, Knights can nerf your damage down into the single digits... Any stronger and they would rightly qualify as a boss.
Foe Romance Subtext: One Heroes' Heart Day event had a Shadowscythe Commander (by the name of Medeia) choose Major Braddock Steele as her soulmate... Un/fortunately, Steele rejects her- stating that his true love is blowing up the Shadowscythe.
Funny Moments: Not in game, but among the dev team: Planet 51 was created by Korin because it was his week to release an update... so he created that entire thing after locking the staff member who's ID is Warlic in a closet FOR FIVE DAYS.
Game-Breaker: The monthly mech from June of 2009, the Warbear, sounds like your average mech... until you check its stats on the forums and discover the damage bonuses on the arm and shoulder weapons. Level 20 and below: 250%, Highest verison: 350%, everything in between: 300%. Not to mention the head weapon will boost attack and accuracy by an additional 10% each turn for 4 turns. The level 20 version could easily beat 2 level 28 enemies in a row. It can beat extreme mode bosses at more than half health. It can win the effing Star Captain bonus challenge at level 25. And the body weapon does guaranteed critical hits. Justified in several cases, though; for example, the giant mech-sized boombox, which came packaged with a CD with a bunch of in-game music on it, is scaled to your level, and is often more effective than most rear shoulders you can find at that level.
