That is the reason I marked it as "Legacy"; it is a testament to my impact on the game, and I am happy with that.

I discontinued it specifically because the developers added a bunch of items that took my ideas and made better versions of them. The Flamewave skill, Acid Spitter Towers, all three spewer guns, Acid Cluster Grenades, Gas Grenades and the Mortar: the devs took my ideas and concepts and truly made them a part of the game, and did a far better job than I ever could.

schade das es nicht mit der aktuellen Version von Riftbreaker kompatibel ist wäre schön wen es das wieder wäre

I will keep that in mind when giving advice in the future...

The new tab is there but i can not use it since i already researched standard grenades before implementing the mod. I wanted to know if i can activate grenade research otherwise (cheats etc.). Sadly i dont think it works but nonetheless looks great enough to try a second playthrough.

As long as you don't have an old version of the mod, adding it mid-campaign should be fine.
Make sure to use a save state that you don't mind accidentally breaking for testing, though.

If it is working, there should be a new tab in the research tree.

Is there any way to activate it mid-campaign?

WARNING:
Due to a change in the research tree, Version 1.4.0 WILL BREAK YOUR SAVES.

For Chinese users: there is now a partial Chinese localization in-game!
Also Polish, Spanish, Portuguese, and Korean.
Feed back on these would be appreciated.

Edge机翻（更正说明）：

消耗性手榴弹的扩展，因为基础游戏中的两种类型之一完全被榴弹发射器所掩盖。

更改：标准手榴弹：

如果它击中地面，则没有以前那么有弹性，因此您需要注意目标。
颜色变为黄色。

重力手榴弹：
略带增益。事情将更难逃脱。

新增：燃烧手榴弹：

火力伤害。减少伤害，但增加半径。点燃生物和植被。

酸性手榴弹：
强大的酸性伤害，但随着时间的推移。

等离子手榴弹：
强大的能量伤害，但半径减小。