I'm not a total master at this game who who has like the top five scores on the highscores, but I'm good enough to share some helpful tips with those who are having trouble.
First off, the first time you play or if your trying to get highscores you should try all the weapons and see which ones work best. While some weapons are better than others, sometimes a personal opinion can be the over ruling factor. What I mean by this is that you should choose the weapons that you like and feel right to you. While there really are no good or bad weapons, here is the general overview of Thing Thing Arena 3's weapons. The weapons of not only this game, but of all the games can be divided into different sub categories. The first (and weakest) sub category of weapons is the pistols. The pistols have a lot of ammo, making them a trusty sidearm. However, they have a slow rate of fire and do not do very much damage, so swap it for a new weapon when you get the chance. The next category is the sub machine guns. The sub machine guns have a great rate of fire but lack accuracy and damage. However, they are a good weapon to have if nothing else is available. The third category is the standard and regular machine guns. These don't have quite as high of a rate of fire as the sub machine guns but have better accuracy and do more damage. Next is the shotguns. They are powerful, but are offset by their slow reloads, slow rate of fire, and inability to carry lots of ammo at a time. The last category is the heavy weapons. You should always, if possible, have one of these all the time. Great damage, most of them have fair rates of fire considering how powerful they are, and they can hold a considerable amount of ammo. For weapons I reccommend having a heavy weapon and a sub machine gun or regular machine gun. Any of the machine guns will do, and for the heavy weapons you should have the gun that looks like a rifle but shoots a powerful lazer instead. This can kill enemies in two hits, carries up to 60 shots, and can damage an enemy through another enemy. The last weapon sub category only contains one weapon, because it is unique from all of the other weapons. This weapon is the harpoon gun, a semi automatic rifle that can shoot harpoons relatively quickly at oncoming enemies. While it doesn't pack much of a punch, it only takes a few harpoons to down an enemy, and carries lots of ammo. I found myself using it a lot for the last two reasons.
The following is a few helpful tips I discovered. The first one is that if you have a weapon that's out of ammo or you simply don't want, press space bar when an enemy is in close proximity. You will automatically chuck the weapon at the enemy, stunning them and simultaneously inflicting a small amount of damage. While this is one of the more obvious tricks this can ultimately help you conserve and save precious ammo for when it is really needed. Also, don't feel afraid to switch to your lead pipe! I think it has been upgraded and now does more damage, plus it has infinite ammo and can't be discarded or lost. Sometimes, it works if you chuck an empty gun at an enemy and then bash their brains out with the lead pipe, and you don't have to use a single bullet! Another tip is that if you are low on health or ammo, you should always know where it can be found. My strategy is to find a place where there is health and ammo and then camp their for a while, racking up lots of kills. As soon as I'm low on health and ammo once again I move to the next area which contains health and ammo and do the same thing. This is especially useful in conjunction with the laser gun. I also found that using the grenade launcher was great for camping out, since every time a group of enemies came to close I would just shoot a grenade, watch the area become green with toxic gas, and then watch triumphantly as my enemies melted before my eyes and lay as a heaping pile of bones. If you have any other questions or need a full list of the weapons leave a comment on my profile. Have fun!
My favorite weapon combo is the magnum and the tavor. The magnum's fun to use and powerful, and when you're low on ammo you whip out the tavor and bring the pain.
Tavor/G18: Long range + short range, simple as that. Good for medium and large arenas
Dual shotties/dual g18s/lead pipe: best for arenas where there's nowhere to hide, run through the enemies blowing there heads off. when your low on health, execution spam
Grenade darts/proxy mines: plant your traps and move on, great for large arenas. when the enemies get close pull out your pipe or art19.
Misc. Tips: executions are a great way to regain health, personally, i change the button from F to C for convenience
you get the artifact 19 after getting 100 kills with every weapon (all the weapon achievements)
If you want the OVER9000 achievement you must try laser+acid+artifact19. Without the artifact19 the combo doesn't work well, but nothing else is that feasible for killing thousands.
I mean to kill 9000 you need to face 4 spawns for over 2000 waves, either you do it with the granade dart double jump (which in the long-run is extremely tiresome), or use acid cheese (you can kill all being untouchable but cannot pick up more ammo since that is too dangerous). The only way to get enough ammo for that is by using laser, such that you can blow them up all at once.