For students who need to focus on an individual vowel sound, PBS Kids has a game called Chicken Stacker (at pbskids.org). This game is ideal for students who are still learning all of their vowel sounds. Students can isolate one vowel sound by choosing one before the game begins. Students play the game by clicking on words that have the correct vowel sound. The goal of the game is to stack five chickens.
ICT Games has an online game students play by reading c-v-c words (at ictgames.com). This game is an online version of the matching game. Students are shown a picture of an object with three words and then click on the correct word that represents the picture. There isn't a way to isolate one specific vowel in order to play the game so students must know all of their short vowel sounds because the words used in the game uses all short vowel sounds.
Kent Trust Web has an online pirate themed game that challenges students to read a mixture of c-v-c words (at kenttrustweb.org.uk). The pirate tosses a coin into the air and students are challenged to read the word. If the students read the word correctly, they are to click the check mark; if the student is unable to read the word, the student will have to sound out the word and read it correctly to move to the next word. This game requires self-monitoring, but a beginning reader may need to be paired with a higher level reader to ensure that the words are read correctly the same way you would if the two students were using flashcards.
For students who can identify short vowel sounds, read c-v-c pattern words and are more advanced, challenge them to spell words using short vowel sounds. Learning Games for Kids has a game that allows students to spell words using a specific vowel letter (at learninggamesforkids.com). After choosing the letter, the game shows the vowel with eight other letters students must use to spell 10 words. After a list of 10 is created, students hear each word read by itself or hear each word used in a sentence. An additional challenge to this activity would be to make students write the sentence they hear.