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