Here is the full list of all 42 STEINS;GATE achievements. It takes around 40-50 hours to unlock all of the achievements on Windows.
Unlocked all Achievements.
[Phone Trigger] Received all 13 RaiNet episode summaries.
[Phone Trigger] Received 4 songs from a chaotic head.
[Phone Trigger] Received all Gero Froggy wallpapers.
Learned about Luka's relationship to his sister.
Made 10 mistakes while attempting to set the PhoneWave (name subject to change)'s timer.
Unlocked all CGs.
Completed all endings.
Reached Steins Gate.
Reached Kurisu's ending.
[Phone Trigger] Learned why Mayuri started making costumes.
Made friends with Kurisu via email.
[Phone Trigger] Offered tea by Faris.
[Phone Trigger] Asked by Kurisu to buy cup noodles twice in a row.
[Phone Trigger] Received an unusual proposition from Suzuha.
Reached Mayuri's ending.
Chapter 9 Clear
Unlocked 75% of CGs.
Chapter 8 Clear
Reached Luka's ending.
Chapter 7 Clear
Reached Faris's ending.
[Phone Trigger] Ignored a phone call.
Chapter 6 Clear
Reached Suzuha's ending.
[Phone Trigger] Cleared someone's mail without reading it.
Unlocked 50% of CGs.
Chapter 5 Clear
[Phone Trigger] Received 3 wallpapers of characters from a chaotic head.
Chapter 4 Clear
Unlocked 25% of CGs.
Chapter 3 Clear
Chapter 2 Clear
Chapter 1 Clear
[Phone Trigger] Received 2 Upa wallpapers.
[Phone Trigger] Changed ringtone.
[Phone Trigger] Changed phone wallpaper.
[Phone Trigger] Viewed email send history at least once.
[Phone Trigger] Replied to an email.
[Phone Trigger] Read an email.
Prologue Clear
Started Steins;Gate.