This guide will probably be rendered inaccurate as doborog updates the game, but these are my tips to get high scores on endless mode, or just in general.
1. Jetpack is OP
Jetpack, in my opinion, is the best upgrade in the game. Allowing you to go by almost any other robot, with this and a bit of energy capacity, you can easily breeze through the first couple tiers of the game. It allows you to outmaneuver all enemies including pesky archers, and is a direct counter to hammer bots due to their slow swing speed.
2. The Swordsmen's Weakness
All swordsmen in the game will almost always die from this one, simple trick: Swing at their flanks. Try to outmaneuver the swordsmen you face by going sideways and using sideswipes, always keeping the enemy in view. By sideswiping and turning sideways as well, you also lengthen your swing. This even works against large groups of enemies and the mk3 and mk4 swordsmen, and is my favorite tactic to kill the swordsmen.
3. Do not disregard the Block Arrows Tree
The Block Arrows Tree may not seem a priority to finish, but the last upgrade is one of the best assets a player can have. Being able to deflect arrows back at targets easily eliminates most stationary archers, and is a good alternate if you yourself do not have a bow.
4. KILL IT WITH FIREEEEEEEEEEE!
Fire is also very useful, and I advise putting this upgrade on whatever your primary weapon is. If you do use fire, always get the second upgrade in the respective tree, as it makes the attack much deadlier. This upgrade turns any glancing blow into a deadly threat, and on a bow, is the easiest way to kill Spider-tron 6000s.
5. Combination Robots don't stand a chance
If anyone is having trouble with mk3 and mk4 combat archers, stop the hassle and transform them into swordsmen! Getting close to these bots will cause them to draw their sword, at which point kill them with part 2 of this guide. If you cannot kill them due to other robots breathing down your neck, stay at a moderate distance from them, as it often takes a bit of time before they take out their bow again.
6. Hammer Bots
To those who feel intimidated by the mk3 hammer bots or are chased down by the fire hammer bots, I have a solution! In an earlier post, as someone said, bows with fire arrows are these bots' weakness, but there is another way! Simply charge through their giant metal hull with your trusty laser sword and jetpack! (Fire upgrades here also help)! As you do, do not turn around to see if your blow killed them, and keep jetpacking until you are clear of their attack range, or us a jump pad (if available) to leap to safety. Then, look back, and they will either be in several pieces or severely damaged.
7. Spider-tron 6000
I have already stated this bot can be kill ed fire arrows between the eyes, but if you unfortunately do not have that upgrade, do not fear. He is a priority while he is undamaged, but wliminate the lesser bots once he is wounded. To do so, take you sword/hammer, and hack away at his giant, spidery legs until he is sufficiently unbalanced. He will be unable to fire at you, the player, effectively, and so the threat of bombs raining down on your face is severely diminished. Then, go kill the other robots and finish him at the end (Breathing flames at him is also fun)
8. The Demons of the Arena... The Jetpack Bots!
I will not lie, these are the toughest bots in this game. A good rule of thumb for these bots is: when in doubt, CHAAAARRRGE! These robots will tend to clump together, and at this point, an effective, but risky, move is to turn on your jetpack afterburners, and with your sword ablaze, charge right through those suckers. Since the bots tend to hold their sideswing, as they turn to strike you, they will often hit each other and soon friendly fire will have killed most of them. At this point. there will be only a few left, which you can dispatch with turning around them and striking them using the swordsmen tactic. os slicing their helpless bodies after kicking them into the dirt.
9. Style is cool!
Not an actual tactic, but it's always fun to look awesome. When on the Fire Island stage, don't slice up those robots, finish them with a kick into the lava and watch as their bodies melt! Only one robot left? Decimate his weak body with some flame-breathing death! ALWAYS go for a decapitation when you are able to, and body mutilation at the end of a fight is good too. Finally, show your savagery by destroying the garbage bots!
This guide is not an end-all-be-all, and not all of these tactics work for everyone. New tactics and suggestions are welcome, and I am not a pro yet, as my high score so far is only a 25. Fight on!