First of all :

Go to "Appdata/Local/shocktr2" and erase everything. It fixed many achievements not popping even if i had already done what it takes to unlock em. Of course you will have to start again from scratch :/ .

>You can "cheat" by editing the values in the "UserDefault" file from that directory.
Example: you didn't unlock the 500 grenades achievement although you used 600+ , just put 499 instead and throw a grenade.

>Some lines in that file may be missing, they only pop in when you use certain item/characters, but ofc it seems bugued too !
Example: you didn't unlock the "Team" achievement although you played with all 4 characters, you may be missing the "character_3" line.

Soooo.... The Achievements :

Complete a stage without dying.
// Well... complete a stage without dying (1st stage in easy mode should be the best way)

Throw 100 grenades (2nd weapon)
// If it doesn't unlock, erase copy/paste this in "Userdefault", then throw a grenade
<GrenadeLaunch>99</GrenadeLaunch>

Throw 500 grenades (2nd weapon)
// If it doesn't unlock, erase then copy/paste this in "Userdefault", then throw a grenade
<GrenadeLaunch>499</GrenadeLaunch>

Play with all characters
// If it doesn't unlock, erase then copy/paste this in "Userdefault", then play with the first character
<character_0_selected>false</character_0_selected>
<character_1_selected>true</character_1_selected>
<character_2_selected>true</character_2_selected>
<character_3_selected>true</character_3_selected>

Complete a stage with full life
// Well... complete a stage with full life (1st stage in easy mode should be the best way)

Complete the game dying more than 40 times
// ...

Complete the game in multiplayer (local or online)
// If you have no friends, just start a game in local coop, let the player 2 die until his continue is wasted, then let his timer run out. Play the game alone, then on the last boss, before you beat him, just press start and select a character with the player 2.

Use all the weapons
// I think there's only 4 weapons (Round, Fire, Missile, Boomerang), i don't know if the character's specific weapons and vehicules count for it.
// If it doesn't unlock, erase thencopy/paste this in "Userdefault", then use the "round" weapon wich can be obtained in the first stage
<Weapon_RoundShot>false</Weapon_RoundShot>
<Weapon_FireShot>true</Weapon_FireShot>
<Weapon_MissileShot>true</Weapon_MissileShot>
<Weapon_BoomerangShot>true</Weapon_BoomerangShot>

Reach a score of 5,000,000 points
// The trick here is to do as much knife combos as possible, otherwise you won't be able to reach the 5kk goal.
Here's a video of a 11.862.860 score

Complete the game using less than 10 credits
// You can start the game in coop, then when you loose your 1st continue, let the time run out and your partner play the game alone. Before he kills the last boss, just press start and get back into the game, finish the boss (without loosing more than 7 credits ofc) and done ! . (if you try it, let me know if it works in local coop)