I did this solo on easy in 1 hour 35 before the end of the second set, by doing the following:
- View the weapons and ammo locations map here: http://halo.wikia.com/wiki/Security_Zone
. Note the locations of the health packs and the Spartan Laser (the yellow L).
- Play any way you like until the 5th wave, where you will be attacked by Brutes with hammers. Grab a hammer and keep hold of it.
- Once you have a hammer, use the B button to melee all enemies (easy mode means you have a lot of stamina). After the 5th kill, you'll get a Hammer Spree medal and after the 10th you'll get a Dream Crusher medal - these are worth big points, especially later in the game when your ratio is 2+. Once you have 10 kills, use a sticky grenade to kill an enemy and reset your hammer spree, then continue to use the hammer. Repeat this pattern.
- Only use the energy on your hammer (the RT attack) against other hammer Brutes to conserve ammo.
- Use the Spartan Laser to destroy Hunters and the Wraiths that periodically spawn at the bottom of the map. Try to do this at the end of a Dream Crusher to maximise your points. The Wraiths pose little threat so take them out at your leisure.
- Keep your Spartan Laser refreshed when a weapon drop occurs. If you run out of ammo, Fuel Rod guns are the next best thing.
- Try to stay near the health packs in case you get into trouble. be careful using the tunnels near the spawn points for cover as it's pretty easy to accidently use a health pack when you don't really need it.
- When the Drones appear, you can either retreat into the spawn point tunnels and use your hammer, or grab a gun turret and get rid of them quickly.
- You'll find that later skulls like Black Eye, Tilt and Famine do not affect you while you're playing in this style (in fact, Black Eye actually helps you).