That Jerboa doesn't allow blocking of instances is a massive red flag. Users need to insist on that functionality and switch to a new app if they don't get it.
It makes violence less fun to play than the alternatives; combat is bullet-time; skill use is a montage. That said, it's not overtly anti-violence, allowing players to figure out that fighting isn't the best approach (or not, if they actually like bullet-time battles).
It rewards experience for solving problems, rather than racking up kills. Modern gaming is too corrupted by the reductive influence of video games and the market-driven need to minimize GM workload to ever really break it of this.
It encourages groups to develop house rules by making changes to the "RAW" only very gradually, instead of constantly reinventing the rules.
I'm here to try to catch the podcast-driven wave of renewed interest in RIFTS to get more people into Palladium-style gaming (the system is broken so you can fix it to your liking).
If you want to recapture the feel of early D&D, ShadowDark (quickstart book) looks like it's going to be pretty good. The simple tweaks to the current game make a big difference, and the artwork is spot-on. This is the image grabbed my attention when I fist saw it (and realized it was new).
Dave Trampier is the most obvious influence, but the art also reminds me of Garry Chalk's illustrations for Joe Dever's Lone Wolf books and the early editions of Talisman. Now that I mention them, Lone Wolf game books and the original Talisman board games are worth familiarizing yourself with if you really want to get into the old-school experience...
I have similarly basic needs, and I stopped distro-hopping when I found Q4OS a few years ago. It seems to run well on most hardware and, while I can't speak as to how well-supported it is in German, its community is based in Germany.