(just a dump of a post by Greng in the Axe, at the moment)
mr driller - set the tone with hi-res puzzle fun in the basic game modes
mr driller 2 - arcade and GBA - refinement to the core game, arcade was nice and fast but gba was somewhat slower… trial mode added about 20 nice set time trials which were welcomed and another character, although i dont think she had different stats in this one (Anna Hotenmeyer).
Mr driller A - GBA release with 'pacteria' collectables and ??? the first of the dori-stone modes.
Mr Driller G - Arcade and PS1 versions - revision of the driller 2 time trials into a nice tiered 'outrun' style series of challenges that had some depth, 'space' mode with random bonus items and endless mode along with decent time trials and score modes. some basic online play but limited to 'at the time' codes and worthless afterwards. Introduced a lot of new characters with different stats to provide variety. Driller Ace also had these characters.
Drill land on Cube - much expansion of game modes but the core game and score attack was wasted somewhat here in favour of casual play.
DS - pretty version but after being used to driller G, was just too slow. Variations on multiplayer based on region of release was dissappointing.
everything since… just version specific without adding anything. everything prior to this point had something unique to offer.