Here is the full list of all 26 Söldner-X 2: Final Prototype Definitive Edition (EU) trophies - there are 14 bronze, 3 silver, 8 gold and 1 platinum.
Collect all other trophies
Clear challenge 'Speed Gunner'
Clear challenge 'Hellfire'
Unlock at least seven specials
Clear challenge 'Stage Keys'
Collect all 15 secret keys in stage eight through ten
Collect all 35 secret keys in stage one through seven
Collect an accumulated total of 77777 chain rings
Defeat the final boss in stage eight in under 115 seconds
Clear challenge 'Action Fan'
Clear challenge 'Chain Expert'
Clear challenge 'Score Collector 1'
Unlock and successfully pass 12 or more challenges
Clear challenge 'Rank Master'
Clear challenge 'Speed Collector'
Clear challenge 'Profiler'
Clear challenge 'Kill Collector 1'
Clear challenge 'Rating Expert'
Complete the tenth stage ('Inner Core') at any difficulty level
Complete the seventh stage ('Van Krist Labs') at any difficulty level
Clear challenge 'Survivor'
Clear challenge 'Collector'
Complete the fifth stage ('Turady Deep Sea') at any difficulty level
Shoot down a rare enemy
Complete the third stage ('Ethia Ruins') at any difficulty level
Complete the first stage ('Zeus Sector') at any difficulty level