Solutions :

3-letter words (1 point): 61

DIF; DIG; DIT; DOF; DOG; DOL; DON; DOO; DOT; EXO; FID; FIG; FIT; FIX; FLU; FOE; FOG; FON; FOU; FOX; FUN; GID; GIF; GIO; GIT; GOD; GOE; GOO; GOS; GOX; IFS; ION; IOS; LOD; LOO; LOT; NOD; NOO; NOT; NUS; OES; ONO; OOF; OON; OOS; OOT; OSE; OUS; SEX; SOG; SOU; SOX; SUN; TID; TIG; TIX; TOD; TON; TOO; UFO; USE.

4-letter words (1 point): 48

DIFS; DIOL; DOIT; DOLT; DOOL; DOON; DOOS; EXIT; FIDO; FIGO; FLUS; FOES; FOID; FOOD; FOOL; FOOT; FOUL; FOUS; FUSE; GIOS; GOES; GOOD; GOOF; GOOL; GOON; IDOL; LOID; LOOF; LOON; LOOS; LOOT; LOTI; LOTO; NODI; NOLO; ONUS; OOFS; OOSE; OXES; OXID; SOOL; SOON; SOOT; SOUL; TOFU; TOOL; TOON; UFOS.

5-letter words (2 points): 15

FIGOS; FIXES; FOXES; GOOFS; GOXES; LOOFS; LOOSE; NOOIT; NOOSE; OOTID; SULFO; TOFUS; TONUS; UNFIT; UNFIX.

6-letter words (3 points): 6

DOOFUS; LOTION; ODIOUS; OTIOSE; SULFID; UNFOOL.

7-letter word (7 points): 1

UNFIXES.