Extra Quality: Project Igi 3 The Plan

It sounds like you're looking for an in-depth guide for "Project I.G.I. 3: The Plan" — specifically regarding an "extra quality" version (likely a mod, repack, or enhanced edition). However, it's important to clarify a key fact first:

What made the originals distinctive

• Emphasis on planning, reconnaissance, and stealth over constant firefights.
• Large, open maps with long sightlines and multiple infiltration routes.
• Limited HUD and minimal hand-holding; mission briefings and player improvisation mattered.
• Realistic weapon handling and an inventory/mission focus rather than arcade-style mechanics.
• A cult following due to unique tone and uncompromising design choices.

Potential pitfalls to avoid

• Sacrificing stealth identity for mainstream shooter tropes.
• Overly scripted levels that kill replayability.
• Poor AI that breaks immersion (either too blind or unreasonably omniscient).
• Neglecting optimization, causing large open levels to stutter on mid-range hardware.

A. Functional Testing

• [ ] No mission script breaks when objectives completed out of order.
• [ ] Save/load system preserves all NPC states, loot, and timers.
• [ ] Fast travel (if implemented) doesn’t duplicate key items.