# Rewards of Success
While many Call of Cthulhu scenarios can be played as a single night of horror, much like a movie, some games can see the investigators developing their skills and going on to tackle other mysteries and challenges. At the end of a scenario or gaming session, the Keeper should say, “Roll for skill increases.” At this time, each player rolls percentage dice (1D100) against any skills that were checked (i.e. skills used and rolled successfully)—if you roll over the current value of the skill (i.e. you fail the skill roll), you get to add 1D10 points to the skill’s value. In other words, the more you know about something, the harder it is to learn anything new or get any better.
Example: Anna (Sarah’s investigator) makes successful use of her Spot Hidden skill during play and so Sarah ticks the box next to that skill on the investigator sheet. After the scenario is completed, the Keeper asks Sarah to roll for skill increases. Anna’s Spot Hidden skill is 45%, and Sarah rolls 43 on the percentage dice. No improvement is made. If she had rolled higher than 45, she would be gaining 1D10 Spot Hidden skill points to raise her ability in that skill. Once she has rolled to check skill increases, Sarah rubs out the ticks on her investigator sheet so it’s now ready for the next game, where she can record new skill successes to check against later.