- "Hordes of aliens vie to destroy you, but nerves of steel and a quick trigger finger give you a solid chance to prevail."
- —Description from Halo: Combat Evolved, Halo 2 and Halo: Combat Evolved Anniversary.
- "Face firm resistance from competent, determined enemies, but burn through enough ammo and you will eventually triumph."
- —Description from Halo 3, Halo 3: ODST and Halo: Reach
- "Face firm resistance from determined enemies. Fight hard and you will triumph"
- —Description from Halo 4
Normal is not too hard, but not too easy. The enemies will not cower as much, and a few Grunts will throw Plasma Grenades. Normal mode has the most realistic strength for Master Chief, Elites and all other Covenant and Marines, though intelligence, enemy accuracy, and enemy numbers are the most realistic in Heroic. Although the strength of the Master Chief is reasonable in Heroic, the strength of the Master Chief is slightly stronger than the Elites in Normal; hence, Heroic is disputably the most realistic mode.
The icon for the Normal difficulty setting is represented with a shield that has the Marathon Logo encrusted into the center. Over the shield is a UNSC Close Quarters Combat Weapon System from right to left.
The most dangerous thing at close range is an Elite with an Energy Sword, and from a distance is a Sniper Jackal with a Beam Rifle. Grunts are still very easy to dispatch of and will more often than not run if the Elite or Brute leading them is killed, which is also fairly easy. Drones and Jackals (with the exception to snipers) are generally the second easiest to kill, even with their unique capabilities. Elites, Brutes, and Hunters are around the same overall in difficulty to kill. It mainly depends on a player's weaknesses as to which enemy is harder to kill.
On the Halo 2 level, Regret, where the player has to kill the Prophet of Regret, his gravity beam will drain around one third of the player's energy shield. He is fairly easy to kill when the player jumps on him and starts punching him. But if the player stays on him for a considerably long time, Regret will teleport away. The Honor Guards protecting him will not do much damage, unless they have Energy Swords.
When the player encounters the Flood, most plasma weapons are average and most human weapons are a bit better. The most effective weapon is the Energy Sword, which will kill a Combat Form in one hit. The second most effective is the Shotgun.The last Most effective weapon is the Spiker. The Flood's unarmed attacks are not that worrying on their own, but if large groups attack the player or he gets hit from behind, then the player has an extremely high chance of being killed.
- Prior to Halo: Reach, every difficulty shield icon had the Marathon symbol on it.
- In Halo 3, Normal difficulty or higher is required for you to collect skulls.
- In Halo 3, you unlock Spartan EVA armor for beating Campaign on Normal difficulty.
- Halo 3, Halo 3 ODST and Halo: Reach keep track of whether you finished Normal Campaign on Solo or Co-op.
- In Halo 3: ODST, the Combat Knife on the difficulty shield icon is replaced with an M7S Caseless Submachine Gun.