Inventory
Buy everything and anything you can here, it will make it easier in the long run.

Recruit Gachi
Always buy the most expensive upgrade you can, they give much more then buying tons of cheaper ones.

Tree of Skills
Invest in skill called "Increases the eff-ness of gachiheroes by 10 percent", this skill combined with "Recruit Gachi" will help you a ton, so you do not have to spam your left click and break your mouse as well as your finger.
Another useful skill to get eventually is "Reducing the cost of buying and crafting weapons by 1 percent."

Time to beat
It takes about max 2 hours to get all the achievements with my method, and most of that time you can just leave the game running in background and every couple minutes check on it, buy upgrades and continue what you were doing :)
Ps. This game has Trading Cards, so when you done with the achievements, high chance you will have 1 or 2 trading cards left to drop, so idle that as well while you are at it.

If you find this guide helpful, I`ll appreciate it if you upvote it and you can check my other Guides.

If i made a mistake, please let me know. I`ll fix it as soon as possible.
If you got a question or suggestion, feel free to leave it in comments and ill consider adding it.

Thank you.