This study explores strain-induced phase transitions from antiferromagnet (AFM) to alternagnet (AM) in ReO₂. The alternagnet is a novel magnetic state with unconventional spin-polarized order, combining properties of both AFMs and ferromagnets. The research demonstrates that compressive strain in ReO₂ can induce a transition from an AFM to an AM phase, lifting the Kramer's degeneracy in the non-relativistic regime and leading to a metal-insulator transition. Spin-polarized angle-resolved photoemission spectroscopy (S-ARPES) is proposed as a method to detect this phase transition. The study combines spin group symmetry analysis and ab-initio calculations to show that the transition occurs in the tetragonal R-phase of ReO₂, which is predicted to be a d-wave AM candidate. The transition is accompanied by changes in the electronic structure and topological properties of the material. The research highlights the potential of strain engineering to control magnetic transitions and opens new avenues for applications in spintronics and data storage. The study also shows that the AM phase in ReO₂ exhibits unique properties, such as spin-splitter currents and non-trivial topological characteristics, which are distinct from conventional AFMs. The findings provide a pathway for controlling magnetic transitions in materials and could lead to new functional materials with tailored magnetic properties.This study explores strain-induced phase transitions from antiferromagnet (AFM) to alternagnet (AM) in ReO₂. The alternagnet is a novel magnetic state with unconventional spin-polarized order, combining properties of both AFMs and ferromagnets. The research demonstrates that compressive strain in ReO₂ can induce a transition from an AFM to an AM phase, lifting the Kramer's degeneracy in the non-relativistic regime and leading to a metal-insulator transition. Spin-polarized angle-resolved photoemission spectroscopy (S-ARPES) is proposed as a method to detect this phase transition. The study combines spin group symmetry analysis and ab-initio calculations to show that the transition occurs in the tetragonal R-phase of ReO₂, which is predicted to be a d-wave AM candidate. The transition is accompanied by changes in the electronic structure and topological properties of the material. The research highlights the potential of strain engineering to control magnetic transitions and opens new avenues for applications in spintronics and data storage. The study also shows that the AM phase in ReO₂ exhibits unique properties, such as spin-splitter currents and non-trivial topological characteristics, which are distinct from conventional AFMs. The findings provide a pathway for controlling magnetic transitions in materials and could lead to new functional materials with tailored magnetic properties.