Here is the full list of all 36 Tony Hawk's Pro Skater 1 + 2 achievements.
Reach Career level 100.
Complete all Gap collections.
Find every alien plushie.
Complete all "Hard" Get-Theres.
Earn the "Legend" Challenge Collection.
Give 50 Letters in Horse.
Earn 5,000,000 points in Trick Attack across all playtime.
Complete every goal in THPS1 Classic and gain all gold medals.
Unlock Officer Dick.
Achieve a judge score of 99.9 on a competition run.
Earn the "Veteran" Challenge Collection.
Create a new park and upload it.
Place 500 objects in CAP.
Earn a score of 10,000,000 in any park in a 2 minute session or single combo. Game Mods must be disabled.
Spend $10,000 in the Skate Shop.
Land a 1,000,000+ point combo.
Achieve a High Score of 1,000,000+ on any classic Park.
Earn 2,000,000 points in Combo Mambo across all playtime.
Paint 100 surfaces in Graffiti across all playtime.
Complete a match in multiplayer.
Find all Stat points for any Pro Skater.
Complete every goal in THPS2 Classic and gain all gold medals.
Get hit by the Bull in Bullring.
Unlock Bullring in THPS2 Classic.
Get hit by a vehicle on every map that features them.
Earn any 4 Medals on competition parks in Tours.
Unlock School II in THPS2 Classic.
Earn the "Rookie " Challenge Collection.
Unlock Roswell in THPS1 Classic.
Bail a 100,000+ point combo.
Earn a Medal on any competition park in Tours.
Break 20 Panes of Glass.
Reach Career level 10.
Land a 50,000+ point combo.
Create a skater using the CAS system.
Unlock School in THPS1 Classic.