Berserk is one of my favorite disadvantages in GURPS. But it's got some wording issues that go all the way back to Roleplayer #1, where it originated.
Right now, strictly read:
- If you trip, your are down and can't stand back up. Change Position is not a valid choice, so, you have to crawl.
- You can't re-ready a weapon that takes readying to use. Double-dagger stat on your weapon? Swing it once, then it's done, you can't do anything about it. No greataxes for berserkers, it's a bad choice.
- If your opponents are too far away for All-Out Attack, you're in luck - Move or Move and Attack, and get defenses.
But honestly, I think the disadvantage works best when it's:
- you lose all defenses, no matter what you do.
- you must attack an enemy if you can reach it.
- you can use Ready to prepare a weapon if it's one that can be done without thought.
- you must attack as frequently and effectively as possible, choosing violent attack over your other options.
How I run it:
When berserk, you lose all defenses, regardless of your maneuver. You simply do not defend, even if your maneuver would otherwise allow it.
You must take All-Out Attack or Move and Attack to attack anything. In the case of M&A, you still can't defend.
You may Ready (or re-Ready) a weapon, if you can ready it without thought (such as Fast-Draw). In general, you will attack with what you have in hand if it's at all effective.
You may Move if that's the only way to get to an opponent, or to Slam.
You may Change Position to regain your feet, get closer to an enemy unreachable without it.
And that's about it.
None of those are exactly written in stone. If any of the above can be lawyered to somehow not act like a frenzied killer trying to deal death to whatever enemy is closest and not stop until those enemies are fallen, then I won't allow the action. If it does, I might allow it anyway - but you still don't get any defenses.
And that's how I run it.