Basically not the best or most interesting tower defense and the start and grinding is not that good. but with that said you can complete it without to much trouble and chill with it a bit.

To get 100% simply play through and complete the game. the only achievement you won't get naturally is to build 50 rockets towers so just find a map, "i used london" one of the last maps and just play it a few times.

I will go over some tips and such on how to beat the game as efficient as possible and general tips to help you through the game.

time to complete: you can count on at least 10 hours i think

Very useful tips to play the game the best way possible. Some obvious, some not, enjoy. hit me up if you want something added.
- you can reset your skills without it costing extra
- slow towers are very good to place around the level and can kill almost all energy monsters if placed around the map and is a great help for slowing down the monsters which greatly helps.
- Its of course a good idea to spread out towers a little but its more efficient and worth more to upgrade usually.
- i found the buff towers fire rate to be the best way of increasing dmg when doing the math.
- make sure to kill all buildings as fast as possible when at the start of a new lvl.

Simply play through the game, there's nothing more to it :), (and 1 more thing). After thats done you'll have to do some grinding building some rocket towers. I used a map called "London" to get the achievement I'm not sure if there's a map with some better possibilites of grinding but that worked for me let me know if you find a better map for getting that last achievement.

can't remember the name, who cares. you just have to build a total of 50 rocket towers. I build some turret towers as shown in the picture and then after having some good enough defenses simply build rocket towers for the rest. and don't spend time upgrading them if going for the achievement since it doesn't add towards the achievement

Its's best to do this on survival but you can also do it in normal mode.

A picture of how i set it up roughly.
have fun

Sadly this is not the best game and you are forced to do some grinding to simply play the game. The only way to do this is to replay levels. Of course this can be done with varying amounts of efficiency.
One of the maps i found useful and one of the points where grinding were a little needed to progress was canyon [ map 3, world 6 ] or level 28 that requires you to use powers instead of towers. I just used whatever towers i found useful I'll put a picture with the setup.

Now you'll have to reset your current upgrades most likely since you won't have upgraded your base and powers enough. don't worry you'll get all gems you use back when resetting. I'll recommend upgrading all the weapons of your base fully and the laser fully. the armor upgrades for the block are also useful and a little for the base itself with at least one healing upgrade is fine.

Now that you've done your upgrades you just have to use lasers when needed and place some blocks so your base doesn't get killed. your towers should be able to take care of themself with minimum upgrades.

Now comes the reason why its an "ok" way to grind. You'll get a bunch of extra coins which at the end will give you bonus gems so you can upgrade more items. also make sure to get three stars since every star is worth 20 gems at that point i think.

good luck let me know if something is unclear

I hope there was some useful info in the guide that were able to help in some way or another. Let me know if something needs to be added or questions and such. And of course, have a nice day.