| Title | Publisher | Year | Language | Documents |
|---|---|---|---|---|
| I Contain Multitudes | Wonaglot | 2021 | English | |
| Illumina | Finn Rosenløv | 2021 | English | Solution |
| Illumina | Finn Rosenløv | 2021 | Danish | Solution |
| Indiana Jones in Wenceslas Square | Primitive Designs | 2021 | English | |
| Infinite Adventure | B. J. Best | 2021 | English | |
| International Cryptex Day | Errol Elumir | 2021 | English | |
| Iron Wolves, The | Chronosoft | 2021 | English | Solution, Map |
| ISS Emergency Christmas Special | ? | 2021 | English |