Dead Island annoyingly only saves at pre-determined points (though this arguably makes it more addictive). To get it to save whenever you want, go to the Controls menu and change the layout from Analog to Digital or Digital to Analog. This causes the game to autosave. You can then obviously change the controls back and carry on playing.
In the hotel during the quest "BORN TO BE WILD," speak to Mike Davies. After that, move to the next room that has a workbench. Enter the next room to find one of the computers to reboot. If you look at the wall to the side of the desk with the fan on it, you will see a poster displaying "Chrome 2," one of Techland's next upcoming games.
On Level 7, you can get a Diamond from the safe in the Mayor's office. If you go back into the sewers, but then turn round and check the safe again, the Diamond should ahve spawned back in there again. Sell the diamonds for tons of money.
-Note: This must be done in solo mode. When you reach a checkpoint during any campaign quest, drop the item on the ground you want to duplicate (if you want, all your items in your inventory). Then, kill yourself by using deobombs or molotovs, When the respawn timer starts counting down, pause the game and reload your checkpoint. When you respawn, all the weapons you dropped will be back in your inventory and also still be laying on the ground where you dropped them. You also do not suffer the cash penalty from dying since you reloaded the checkpoint.
-Note: This trick does not work with projectile weapons. Hold LB then hold RB + Y. If done correctly, there should be two of the same weapon on the ground and it will show that you threw and dropped the same weapon. Repeat this as many times as desired. You can use this trick to make money in game or in online play, and you can supply teammates with strong weapons. You can also duplicate a weapon instead of repairing it. Note: This also works with modified and upgraded weapons.
Note: This can only be unlocked with Sam B after unlocking his Tackle ability. Play Chapter 16, "Locked Up". Once you reach the checkpoint where you have to "Find another way to the cell block control room", go around to get to the control room. When you open the door to the cell blocks, there is a stairway going down and there you will see the Ram. Let him follow you upstairs and go back in the hallway. Leave the door open. The Ram will try to ram you down, but he won't be able to get past the door. This is where you can weaken him until his life is close to dead. Then, deliver the final blows with you Tackle ability.
Pull out the weapon you want to duplicate and wield it. In digital fighting control scheme, hold the left trigger as if to throw the weapon, hit the Y at the same time as you pull the right trigger to throw the weapon. If timed correctly you will throw your weapon and drop a second copy at whatever the current durability of the weapon you dropped was. Keep doubles of your favorite weapon and use it until it breaks, then discard and copy the fully repaired version to ensure you're never stuck with a broken weapon.
ACHIEVEMENT - HOW TO UNLOCK 10 heads are better than 1 (15) - Kill 10 zombies in a row with headshots. A taste of everything (25) - Kill a zombie with 10 different melee weapons. A very special day (30) - Kill 250 zombies with modified weapons. Ah! Spoiled meat! (10) - Kill a Butcher using an axe. Banoi Redemption (30) - Complete act IV. Busy, busy, busy (60) - Finish 75 quests cumulatively. Can't touch this (20) - Use a hammer to kill a series of 15 zombies without taking damage. Cardio (10) - Travel a distance of 20 kilometers on foot. Catch! (10) - Kill an Infected with a grenade blast. Dedicated student (25) - Reach level 25. Everybody lies (20) - Use a large medkit to heal an injury of 5% or less. First! (15) - Kill a Suicider with a grenade. Gesundheit! (10) - Heal yourself with a medkit 100 times. Going steady (25) - Complete 25 quests while playing with at least one co-op partner. Gotta find'em all (20) - Find 60 collectibles. Guns don't kill but they help (25) - Kill 250 zombies using firearms. Hack & slash (25) - Kill 250 zombies using edged melee weapons. Hell in paradise (30) - Complete act I. How many days exactly? (10) - Play Dead Island at least 28 days after starting it for the first time. Humanitarian (15) - Kill 50 human enemies. I want one of those (30) - Customize 25 weapons. Karma-geddon (15) - Kill 50 zombies using a vehicle. King of the jungle (30) - Complete act III. Knock, knock (15) - Breach a locked door with the first blow. Learning the ropes (10) - Reach level 10. Light my fire (20) - Set 10 zombies on fire simultaneously. Ménage à trois (25) - Complete 5 quests with 3 co-op partners. Nearly there (25) - Find 120 collectibles. Need a hand? (10) - Join another player's game. No raccoons in here (30) - Complete act II. Oh, no you don't (10) - Kill a Ram using tackle skill. One is all I need (20) - Kill 5 Infected in a row with a single blow. Originality (10) - Play in a co-op team of 4 different playable characters. People Person (10) - Play with 10 different co-op partners for at least 15 minutes each. Rageman (25) - Kill 100 enemies with Fury attacks. Right 4 Life (30) - Complete act I with 4 different characters. Road Trip (10) - Drive a total distance of 10 kilometers. Rootin' Tootin' Lootin' (30) - Loot 5 Exceptional Weapons. Savior (20) - Save 5 people besieged by zombies. School of hard knocks (30) - Reach level 50. Steam Punk (30) - Create weapons to rival the gods of fire or thunder. Swing them sticks (25) - Kill 150 enemies using Analog Fighting controls. Tae Kwon Leap (25) - Kill 25 zombies with your bare fists. There and back again (30) - Explore the entire island. Tis but a flesh wound! (10) - Sever 100 limbs. To put it bluntly (25) - Kill 250 zombies using blunt melee weapons. Together in the light (10) - Complete 5 quests in a single co-op game with the same partners. Warranty Void if Used (10) - Create a customized weapon.
"Bloodbath Arena" achievements ACHIEVEMENT - HOW TO UNLOCK Complete a set (15) - Kill enemies of 6 different types during a single round. Death Incarnate (50) - Survive wave 30. Extreme Firefighting (25) - Set 5 enemies on fire and then kill them with explosives. Fancy (25) - Survive 10 consecutive waves using only custom weapons. Gladiator school (25) - Survive 15 consecutive waves with each of the 4 characters. Looking for trouble (15) - Survive 5 waves in each of the 4 Arenas. Morituri te salutant (30) - Survive 30 consecutive waves with at least one co-op player. Out of honey? Chew bees! (25) - Survive 5 waves using only your fists and legs. Stick it to the enemy (30) - Survive 15 consecutive waves using the analog combat controls. Wave and Smile (10) - Play any Arena in co-op.
As Logan, hold down the aim button (left trigger) and hold down the fury button while aiming at multiple zombies. Then, pull the right trigger. Instead of logan using his knives, he will be throwing your equipped weapon. Throwing the weapons will cause the game to duplicate your equipped item.
At the warehouse, get the Hammer and Baseball Bat, then fast travel to the Church and sell them to get about $400. Go back to the Warehouse and the Hammer and Baseball Bat will have respawned. Repeat this as many times as you can. Note: You must be in the City and have discovered both the Church and the Warehouse to do this trick.