Both attack and heal power are random numbers between minimum and maximum shown in the description of the skill unless it crits. Critical hits and heals are calculated by formula: 2×MaxPower. Since all crit skills caps at 80% (level 80) it means that 4 out of 5 hits will crit.

Basically it means if your Warrior dealing 475-950 damage and have 80% chance to crit then 4 out of 5 hits will deal 2×950 = 1900 damage and the rest will be (475+950)/2 ­= 712.5 on average.

Click Powers:

• Attack - useful only at the start of the game and when script-spammed. Later on in the game monsters will have too much health to actually bother to click on them. Warrior will deal much more damage than you anyway.
  
• Heal - very useful during the boss battles. Later on in the game is only useful during the dragons battles at the end of each chapter.
  
• Crit - caps at level 80 and affects both Attack and Heal.

Warrior:

• Attack - the one and only damage skill which worth leveling up in the game as much as you can since it producing highest increase in damage per level.
  
• Speed - caps at level 100 and determines how fast your warrior swings his weapon. Useless at the low levels but starting to be vital ~ level 50 and above since it reduces time between attacks to 0.15 sec when it caps and even at level 50 it doubles the damage output.
  
• Health - absolutelly vital skill to survive boss fights because bosses are dealing tremendous amount of single-hit damage. During the first 100 game levels should be rised at least to 60, leter on it's better to keep it close to the current game level. It really matters only during the fights with dragons later on in the game, though.
  
• Crit - caps at level 80 and seriously affects warrior's attack power. Ignore it at the beginning, but cap it out as soon as possible. Starts being noticeable around level 25.

Mage:

• Power - the only consistant source of healing in the game. Don't spend too much gold and gems on it, though. It won't heal you faster than mage's cast speed. All extra levels will go to overheal and will do literally nothing until you upgrade Warrior's health.
  
• Speed - caps at level 130 (cast every 0.3 sec) and absolutelly vital past game level 100.
  
• Will - mage's analogue of Crit skill, caps at level 80 same as any other crit skills in the game. Reduces necessity to upgrade mages power by the factor of 2 when reaches level 50-60.

Just keep in mind that he won't heal more HP than your warrior have. So, if he have ~2000 HP and mage's Will is already past level 50 then rise his Power to 500-1000 healing per cast and stop at this point until you rise warriors HP higher.

Rogue:

• Stun - caps at level 100 and stuns your enemy for up to 1 second at that point for each arrow hit (seems like depends on the enemy's speed). Useless at the start of the game but absolutely vital past level 199. It can stunlock your enemies if applied fast enough. When both Stun and Speed is capped Rogue is capable to stunlock even bosses for a while.
  
• Speed - caps at level 145 and speeds up arrows shooting (every 0.25 sec). Seems like arrows deals no damage, so it only affects Stun. Absolutely vital for stunlocks.
  
• Poison - rogue's damage skill, applied when first arrow hits an enemy and then doing continuous damage, independent from his shooting speed. Grows the same as warrior's Attack, but (!) can not crit.
  
• Potency - speed analogue for Poison hits, caps at level 112 (hit per 0.15 sec). As useless as Poison.

Both Poison and Potency is useful only for level 5000 achievement since relatively cheap to raise when the rest caps at 99.999. When Poison price caps it's pointless to raise anywhere higher. Better spend that gold at warrior's Attack power.

• Click attack power and crits are rather useless, so you can stop upgrading them as soon as you get access to the Warrior's attack power. Click healing will remain useful during the boss fights for a while, though. Especially if scripted.
  
• Before game level 100 focus on upgrading warrior's Attack, Health and Crit; mage's Power and Will; and rogue's Poison. You can simply ignore Speed of all characters and rogue's Stun and Potency for now since they provide next to non-existent difference at the beginning. Most likely you will end up with 50-70 points in each when you get to the level 100.
  
• Do not invest too many points into the mage. Before you upgrade his Will to L50 just make sure he can heal the warrior in 1 cast. With Will L50 and above keep his max heal equal to half of warrior's HP.
  
• When you reach level 100 you can start investing some serious money into Speed of all characters and rogue's Stun capability. They are pretty much useless at the beginning, but provide very powerful results when capped.
  
• Farming gold is significantly faster at the earlier levels. Go back to a place where the warrior can kill enemies in 1-2 hits and leave the game running. For me, it was a game level 75, but I got to the game level 600 at that point. Do not close it and make sure not to minimize its window since the game will be paused in such case.
  
• Using tactic above you can also farm monster kills for the related achievements. That will take at least a week and probably more of a nonstop farm, though. At least you won't need to touch it while it works.
  
• Blue gems are very useful. You can upgrade your stats 1 level per gem and you can buy some useful upgrades with them. I'd recommend focusing on getting 3 upgrades to Banker first (15 gems), then upgrade your warrior and mage ranks twice (these +25% bonuses, 5 gems per upgrade). Upgrading rogue is almost useless since it affect only his Poison attack power and Poison is too weak. You better buy a familiar for these gems, though. His power is similar to poison, but you don't have to invest any money and gems above that to upgrade him. You will need 15 gems to upgrade him to the max power. If I'm not mistaken his level 2 and 3 upgrades are only available after game level 100, though.
  
• Do not waste your gems to buy the Inn or Potions. Inn is almost entirely useless because normal monsters are weak and the mage will heal the Warrior almost instantly anyway. The inn is only good to survive the first hit from the bosses and usually you will come there at the full HP anyway.
  
• Also, do not waste them at the click powers. They dosn't lasts long enough, have a very long cooldown and useless overall. You may want to buy them soon only to speed up the achievement for using them 150 times, but most likely you will play this game long enough to do so later on when you will have much more gems to spend. I'd recommend to buy them past level 200.
  
• To cap out Crit and Speed at the game level 100 and buy other stuff for gems you may want to use a glitch (?) in the game which gives you gems every time when you reach game levels 100, 200 and 300 (1, 2 and 3 gems respectively). To do so go to the level 99 (199, 299), exit from the game, start the game, go to the next level (100, 200, 300), go 1 level back and exit from the game. Rinse and repeat. Each gem = 1 skill level. I wrote a script to automate this for the 3 gems case, but if we consider the time required to farm at the early levels for monster kills it may not be very useful.

There are many achievements, but they all fall into 9 categories with the same type of goal within each category and just different numbers.

• Upgrading stats - it's a sum of all upgrades on all characters and clicks stats. You will get ~1000-2000 stats levels naturally during the first few days of playing the game and the rest is easier to get during farming monster kills for the other achievements. Also, you can get some levels throug the gems glitch by farming some gems, but it culd be a huge waste of your time. You can grind gems automatically with the script provided in the following section, but it's tested only with a switch between game levels 299→300.
  
• Defeating monsters - you will get first 3 naturally, but reaching Knight and Tap Hero will require some time spent on the first levels where you can kill enemies with 1 hit. So, get back to them later when you will have some free time to let it run in the background.
  Please note that monster kills farming achievements are the most time consuming. In the best case you kill 1 monster in 1 second, so 1M monsters for the last achievement will take 10~12 days of non-stop grind. As long as you stay at the level where 1 coin drops 125 gold on average you will get enough gold for 5000 levelups for the upgrading stats achievement, so instead of staying at level 1 try to go a little further. I'd recomment levels 61-99.
  
• Acquiring gold - all 5 will come naturally.
  
• Clicks - most likely you will get first level naturally, but the rest is just crazy. Last one requires you to click 250 000 times. Almost impossible unless you expect to play this game forever. Very easy to automate, though. Just leave my script clicking at the enemies or your party overnight. Combine it with monster kills achievements if you wish.
  
• Finding chests - will come naturally. Most likely by the end of section 301-400.
  
• Cast powers - there are 6 powers in the game. Buy them with gems (3 gems each) and cast them each time when they cool down. You need to cast them 150 times to get all 5 associated achievements.
  
• Collecting gems - all 5 will come naturally.
  
• Reaching game levels - same as above, all 5 will come naturally. You will get the last one as soon as you enter game level 300.
  
• Killing bosses - all 5 will come naturally during the first 100 game levels. You will meet the first boss at the level 5 then at the level 10 and 7 more each 10 levels up to the level 80. The last one will be at the level 100. Use click-healing to survive during these fights.

You will need to use AutoHotkey tool for this: http://www.autohotkey.com/
Click "Download AutoHotkey" in the site header and install it.

Now create new file with the name script.ahk.
To do so open Notepad, paste there code providede below and save it with the name given above. Make sure it's ".ahk" and not ".txt".

Code:

If your game closes with an error message then try to change "; Now exit" part to this:

Now when you created that script file simply run it by double-clicking it. If everything right green icon with letter H will appear in the system tray (could be auto-hidden).

From this point, your keys E, R, T and Z will perform some special actions if pressed. Don't leave this script running when you want to do something else besides playing this game! Right-click at the AutoHotkey icon and either Suspend script (letter on the icon will change to S) or exit from the AutoHotkey.

T - stops all scripts from running.
E - if pressed generates a huge amount of clicks at the current mouse pointer position.
R - designed to work in the game windowed mode, searches for the game, brings it to top and then continuously performs clicks on the warrior and his enemy to heal and attack at the same time. Actually not very useful since between bosses you may want to use only attack and during the boss fights it's better to stick to healing only.
Z - also designed to work in the game windowed mode, grinds gems, requires some extra preparations described below.

Preparations before pressing Z to grind gems:

• You have to reach game level 300 and be capable of surviving 1-2 hits from the boss there. You may test it when you reach level 100 and 200, though, but most likely it won't work properly. Actually I made it when reached game level 400.
  
• You better buy Inn from Extra Shop since it slightly raises your chances to survive 1-2 hits from the boss at the beginning and if you die script may not work correctly during the consequent runs. In the best case it will waste 1 game re-run, though. I've died once during the testing and it returned back to normal during the next re-run.
  
• Return to the game level 299.

Now press Z and look how it goes.

Script supposed to run the game, skip the welcome screen, press forward to the next game level, press backward to the previous game level and close the game. It may return back more than 1 level in some rare cases, so you may want to stop and restart it if this happens. Well, not really important, just will waste some grinding time before you stop it and re-run from the proper game level again.

If it can't run the game then, most likely, path to the game in the script is wrong. This may happen if you installed Steam or the game into a non-default folder or you are using a 32-bit system, or your system drive's letter isn't "C". Script assumes that game's executable file is located here: c:\Program Files (x86)\Steam\steamapps\common\Tap Heroes\Tap Heroes.exe
If the actual path is different then find that path in the script and replace it with the proper one.

Also for some people it starts the game but doesn't move forward and backward. Unfortunately, I have no idea why and not sure how to help. Well, it isn't much useful anyway.