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