Hmmm... it's tough to say since different game genres usually require different set of SFX.

So I'll just post generic SFX that I usually need when creating a game:

1. Menu SFX : click, move from text to text/option to option

2. Explosion SFX : small, medium and large explosion

3. Shooting SFX: this could vary depending on number of weapons but at least player's and enemies' should have their own shoot SFX

4. Action SFX: jump, land on ground, step

5. Fight SFX: generic hit FX, slash hit FX, non-slash hit FX, death, block

6. Shop SFX: caching, buzzt (purchase denial), coin pick up

7. Breaking SFX : broken wood, broken metal, broken rock etc

The most "normal" sound effects that I'm having trouble finding are detailed melee combat sound effects.  Things like X weapons hitting Y armors at various speeds and angles, either penetrating or failing to penetrate, several variations of each combination for variety.

Less normal, more specialized, and much harder to record would be animal sounds.  Complete, accurate animal sound sets for as many individual species as possible.  Especially for songbirds, where closely related species can have totally different songs.