Here's a rough development timeline:
In 2001, Inferno was born and campaign was partitioned into three releases: R1, R2, and R3. In 2003, INF R1 was released. With the rise of the SCP, we decided to fuse R1, R2, and R3 into one new release, known as INF SCP, whose development went on sporadically for the next several years. It was put on the backburner as focus was transferred to Inferno: Alliance (or INFA) and its sequel INFSA once INFA was released. Last year, a team member brought up resurrecting R1 and bringing it to modern standards. Various plans were looked at, and we ultimately decided to fuse R1 with what we have in development for INF SCP into a new release that will complete the R1 story arc. This is our currently active project: Inferno Release 1 Upgrade, or INFR1U.